Ch 9 Alterations in Immunity and Inflammation
What antibody binds to a mast cell? a. Cytotropic b. Allergen c. Antigen d. Fc
A A cytotropic antibody (also called a reagin) is the antibody that binds to the mast cell. An allergen is an environmental antigen that induces an allergic response. An antigen stimulates the immune response and antibody to bind to the mast cell. The Fc is the portion of the mast cell where IgE binds.
Which statement is true regarding hypersensitivity reactions? a. They require sensitization against a particular antigen. b. They occur after the primary immune response. c. Reactions are always delayed. d. The most delayed reaction is anaphylaxis.
A A hypersensitivity reaction requires sensitivity to an antigen and occurs after an adequate secondary immune response. These reactions may then be immediate or delayed. The most immediate reaction is anaphylaxis.
Which definition is true? a. Allergy means the deleterious effects of hypersensitivity. b. Immunity means an altered immunologic response. c. Hypersensitivity means the protective response to an antigen. d. Autoimmunity means the normal response to foreign antigens.
A Allergy means the deleterious effects of hypersensitivity to environmental antigens. Immunity is an organism's ability to resist disease. Hypersensitivity is an altered immunologic response to an antigen that results in disease or damage to the host. Autoimmunity is a disturbance in the immunologic tolerance of self-antigens.
Which statement is true of serum sickness? a. Immune complexes are formed and deposited in target issues. b. Immune complexes are formed and deposited in the blood vessels. c. It is considered a Type II hypersensivity response. d. Cytotoxic T lymphocytes are responsible for the condition.
A Serum sickness reactions are caused by the formation of immune complexes in the blood and their deposition in target tissues. An Arthus reaction deposits complexes into the walls of blood vessels. Serum sickness is a Type III hypersensitivity reaction. Type IV mechanisms occur through either cytotoxic T lymphocytes or lymphokine-producing T-helper (Th) 1 cells.
Histamine release leads to which of the following? (Select all that apply.) a. Bronchial smooth muscle contraction b. Bronchoconstriction c. Decreased vascular permeability d. Vasoconstriction e. Edema
A,B,E Histamine contracts bronchial smooth muscle, which causes bronchoconstriction. Vascular permeability, edema, and vasodilation also increase.
35. A person with type O blood is considered to be the universal blood donor because type O blood contains which of these? a. No antigens b. No antibodies c. Both A and B antigens d. Both A and B antibodies
ANS: A Because individuals with type O blood lack both types of antigens, they are considered universal donors, meaning that anyone can accept their red blood cells. Type O individuals, who have neither A or B antigen but have both anti-A and anti-B antibodies, cannot accept blood from any of the other three types.
10. When mismatched blood is administered causing an ABO incompatibility, how are the erythrocytes destroyed? a. Complement-mediated cell lysis b. Phagocytosis by macrophages c. Phagocytosis in the spleen d. Natural killer cells
ANS: A Erythrocytes are destroyed by complement-mediated lysis in individuals with autoimmune hemolytic anemia or as a result of an alloimmune reaction to ABO-mismatched transfused blood cells. Erythrocytes are not destroyed by phagocytosis or natural killer cells.
34. Which statement is true regarding immunodeficiency? a. Immunodeficiency is generally not present in other family members. b. Immunodeficiency is never acquired; rather, it is congenital. c. Immunodeficiency is almost immediately symptomatic. d. Immunodeficiency is a result of a postnatal mutation.
ANS: A Generally, the genetic mutations that cause immunodeficiency are sporadic and not inherited; a family history exists in only approximately 25% of individuals. The sporadic mutations occur before birth, but the onset of symptoms may be early or later, depending on the particular syndrome. The immunodeficiency can be either congenital or acquired.
7. A patient is having an IgE-mediated hypersensitivity reaction. What action by the healthcare professional is best? a. Give the patient an antihistamine. b. Prepare to give the patient a blood transfusion. c. Ask the patient is he/she is having pain at the site. d. Apply warm, moist heat to the affected area.
ANS: A Histamine is the most potent mediator in an IgE-mediated hypersensitivity reaction (Type 1). Histamine bound to H2 results in the degranulation of mast cells with the release of histamine. Blocking histamine receptors with antihistamines can control some type I responses. The healthcare professional would not need to give the patient blood; warm; moist heat; or ask about pain.
36. Immunoglobulin E (IgE) is associated with which type of hypersensitivity reaction? a. I b. II c. III d. IV
ANS: A Hypersensitivity reactions have been divided into four distinct types: type I (IgE-mediated) hypersensitivity reactions, type II (tissue-specific) hypersensitivity reactions, type III (immune complex-mediated) hypersensitivity reactions, and type IV (cell-mediated) hypersensitivity reactions.
18. A healthcare professional is teaching a patient about Raynaud phenomenon and instructs the patient to avoid cold. What is the best explanation of how cold impacts the manifestations of this disease? a. Immune complexes that are deposited in capillary beds, blocking circulation b. Mast cells that are bound to specific endothelial receptors, causing them to degranulate and creating a localized inflammatory reaction that occludes capillary circulation c. Cytotoxic T cells that attack and destroy the capillaries so that they are unable to perfuse local tissues d. Antibodies that detect the capillaries as foreign protein and destroy them using lysosomal enzymes and toxic oxygen species
ANS: A Raynaud phenomenon is a condition (type III hypersensitivity reaction) caused by the temperature-dependent deposition of immune complexes in the capillary beds of the peripheral circulation. The healthcare professional should teach the patient to avoid cold or to wear gloves to mitigate the cold. None of the other options are involved in causing this condition.
14. Graves disease (hyperthyroidism) is an example of which type II hypersensitivity reaction? a. Modulation b. Antibody-dependent cell-mediated cytotoxicity c. Neutrophil-mediated damage d. Complement-mediated lysis
ANS: A The antibody reacts with the receptors on the target cell surface and modulates the function of the receptor by preventing interactions with their normal ligands, replacing the ligand and inappropriately stimulating the receptor or destroying the receptor. For example, in the hyperthyroidism (excessive thyroid activity) of Graves disease, autoantibody binds to and activates receptors for thyroid-stimulating hormone (TSH) (a pituitary hormone that controls the production of the hormone thyroxine by the thyroid). Graves disease is not a result of cell-mediated cytotoxicity, neutrophil-mediated damage, or complement-mediated lysis.
22. A patient asks the healthcare professional why tissue damage occurs in acute rejection after organ transplantation. What response by the professional is best? a. Th1 cells release cytokines that activate infiltrating macrophages, and cytotoxic T cells directly attack the endothelial cells of the transplanted tissue. b. Circulating immune complexes are deposited in the endothelial cells of transplanted tissue, where the complement cascade lyses tissue. c. Receptors on natural killer cells recognize antigens on the cell surface of transplanted tissue, which releases lysosomal enzymes that destroy tissue. d. Antibodies coat the surface of transplanted tissue to which mast cells bind and liberate preformed chemical mediators that destroy tissue.
ANS: A The recipient's lymphocytes interacting with the donor's dendritic cells within the transplanted tissue usually initiate sensitization, resulting in the induction of recipient Th1 and Tc cells against the donor's antigens. The Th1 cells release cytokines that activate infiltrating macrophages, and the Tc cells directly attack the endothelial cells in the transplanted tissue. The other options do not accurately describe how acute rejection after organ transplantation results in tissue damage.
27. A child in the clinic has an absence of a parathyroid gland, structural heart defects, and a shortened structure of the upper lip. What immune dysfunction does the healthcare professional suspect? a. Partial-to-complete absence of T-cell immunity b. X-linked recessive microcephaly c. An autoimmune disease like systemic lupus erythematosus d. Adenosine deaminase deficiency
ANS: A This child has the clinical features of DiGeorge disease, which is caused by a partial-to-complete absence of T-cell immunity.
3. The common hay fever allergy is expressed through a reaction that is mediated by which class of immunoglobulins? a. IgE b. IgG c. IgM d. T cells
ANS: A Type I reactions are mediated by antigen-specific IgE and the products of tissue mast cells. The most common allergies (e.g., pollen allergies) are type I reactions. In addition, most type I reactions occur against environmental antigens and are therefore allergic. Hay fever allergy is not mediated by IgG, IgM, or T cells.
40. Which disorders are considered autoimmune? (Select all that apply.) a. Crohn disease b. Addison disease c. Rheumatoid arthritis d. Systemic lupus erythematosus e. Type 2 diabetes
ANS: A, B, C, D Crohn disease, Addison disease, rheumatoid arthritis, and systemic lupus erythematosus are all diseases that result from autoimmune pathologic conditions. Insulin-dependent diabetes is also an autoimmune disorder, but type 2 diabetes is not.
39. Exposure to which of these could result in a type IV hypersensitivity reaction? (Select all that apply.) a. Poison ivy b. Neomycin c. Dairy products d. Nickel e. Detergents
ANS: A, B, D, E Allergens that primarily elicit type IV allergic hypersensitivities include plant resins (e.g., poison ivy, poison oak); metals (e.g., nickel, chromium); acetylates and chemicals in rubber, cosmetics, detergents; and topical antibiotics (e.g., neomycin). Food products typically result in type I hypersensitivity reactions.
41. Which statements best define acute rejection? (Select all that apply.) a. Acute rejection is a cell-mediated immune response. b. Acute rejection is usually a type III rejection. c. Immunosuppressive drugs delay or lessen the intensity of an acute rejection. d. Acute rejection is associated with the body's response to an organ transplant. e. Acute rejection is a response against unmatched human leukocyte antigens (HLAs).
ANS: A, C, D, E Acute rejection is primarily a cell-mediated immune response that occurs within days to months after transplantation. This type of rejection occurs when the recipient develops an immune response against unmatched HLAs after transplantation. A biopsy of the rejected organ usually shows an infiltration of lymphocytes and macrophages characteristic of a type IV reaction. Immunosuppressive drugs may delay or lessen the intensity of an acute rejection.
4. What are blood transfusion reactions an example of? a. Autoimmunity b. Alloimmunity c. Homoimmunity d. Hypersensitivity
ANS: B Alloimmunity (also termed isoimmunity) occurs when the immune system of one individual produces an immunologic reaction against tissues of another individual. Autoimmunity is a disturbance in the immunologic tolerance of self-antigens. Homoimmunity refers to the resistance of a lysogenic bacterium that is carrying a phage to an infection by the same type of phage. Hypersensitivity is an altered immunologic response to an antigen that results in disease or damage to the host.
20. An Rh-negative woman gave birth to an Rh-positive baby. When discussing Rho[D] immunoglobulin with her, what information should the healthcare professional provide? a. It provides protection against infection from poor immunity in the baby. b. It prevents alloimmunity and hemolytic anemia of the newborn. c. It provides necessary antibodies in case the mother doesn't breastfeed. d. It causes the intestinal tract of the newborn to produce antibodies.
ANS: B Alloimmunity occurs when an individual's immune system reacts against antigens on the tissues of other members of the same species. This can occur when a woman is Rh-negative and gives birth to an Rh-positive baby, leading to hemolytic anemia of the newborn. Rho[D] immunoglobulin does not provide protection against infection, provide antibodies to a bottle-fed baby, or cause the intestine to produce antibodies.
15. Type III hypersensitivity reactions are a result of which of these? a. Antibodies coating mast cells by binding to receptors that signal its degranulation, followed by the discharge of preformed mediators b. Antibodies binding to soluble antigens that were released into body fluids and the immune complexes being deposited in the tissues c. Tc cells or lymphokine-producing Th1 cells directly attacking and destroying cellular targets d. Antibodies binding to the antigen on the cell surface
ANS: B Antigen-antibody (immune) complexes that are formed in the circulation and then deposited later in vessel walls or extravascular tissues cause most type III hypersensitivity diseases. Type III hypersensitivity reactions are not the result of antibodies coating mast cells to signal their degranulation, immune cells directly attacking and destroying targets, or antibodies binding to the antigen on the cell surface.
33. Which statement is true concerning an atopic individual? a. They tend to produce less IgE. b. They tend to produce more Fc receptors. c. They tend to attract very few mast cells. d. They tend to produce very high levels of IgM.
ANS: B Atopic individuals tend to produce higher quantities of IgE and have more Fc receptors for IgE on their mast cells. Atopic individuals tend to produce more, not less, IgE. Manifestations these individuals display are influenced greatly by the release of histamine from mast cells, which are found in large numbers in the affected tissue. An IgM response is a mainstay of type II responses.
2. What is a hypersensitivity reaction that produces an allergic response called? a. Hemolytic shock b. Anaphylaxis c. Necrotizing vasculitis d. Systemic erythematosus
ANS: B Examples of systemic anaphylaxis are allergic reactions to beestings, peanuts, and fish. Hemolytic shock would be a state in which erythrocytes are destroyed by complement-mediated lysis to the point of causing a state of shock. Necrotizing vasculitis is inflammation of blood vessel walls that limits perfusion. Systemic lupus erythematosus (SLE) is a chronic, multisystem, inflammatory disease and is one of the most common, complex, and serious of the autoimmune disorders.
37. A pregnant woman has Graves disease. What test/s does the healthcare professional advise the woman about? a. Frequent tests of the newborn's muscular strength and movement. b. Blood test for hyperthyroidism c. Monthly OB checkups for fetal anomalies or pregnancy loss d. Serum complete blood count including platelet count
ANS: B Graves disease is an autoimmune disease in which maternal antibody against the receptor for TSH causes neonatal hyperthyroidism. The healthcare professional should advise the woman that her newborn will need to be tested for hyperthyroidism.
19. Deficiencies in which element can produce depression of both B- and T-cell function? a. Iron b. Zinc c. Iodine d. Magnesium
ANS: B Of the options available, only deficient zinc intake can profoundly depress T- and B-cell function.
29. Considering the effects of nutritional deficiencies on the immune system, severe deficits in calories and protein lead to deficiencies in the formation of which immune cells? a. B cells b. T cells c. Natural killer cells d. Neutrophils
ANS: B Severe deficits in calorie or protein intake lead to deficiencies in T-cell function and numbers. B cells, natural killer cells, and neutrophils are not necessarily affected by nutritional deficits.
32. Raynaud phenomenon is an example of which type of hypersensitivity? a. IV b. III c. II d. I
ANS: B The characteristics of serum sickness are observed in only systemic type III autoimmune diseases such as Raynaud phenomenon.
38. When a tuberculin skin test is positive, the hard center and erythema surrounding the induration are a result of which of these? (Select all that apply.) a. Histamine b. T lymphocytes c. Immune complexes d. Products of complement e. Macrophages
ANS: B,E The reaction site is infiltrated with T lymphocytes and macrophages, resulting in a clear hard center (induration) and a reddish surrounding area (erythema).
11. When antibodies are formed against red blood cell antigens of the Rh system, how are the blood cells destroyed? a. Complement-mediated cell lysis b. Phagocytosis by macrophages c. Phagocytosis in the spleen d. Neutrophil granules and toxic oxygen products
ANS: C Antibodies against platelet-specific antigens or against red blood cell antigens of the Rh system coat those cells at low density, resulting in their preferential removal by phagocytosis in the spleen, rather than by complement-mediated lysis. These blood cells are not destroyed by complement-mediated cell lysis, phagocytosis by macrophages, neutrophil granules, or toxic oxygen products.
8. What characteristic do atopic individuals have that make them genetically predisposed to develop allergies? a. Greater quantities of histamine b. More histamine receptors c. Greater quantities of IgE d. A deficiency in epinephrine
ANS: C Atopic individuals tend to produce higher quantities of IgE and to have more crystalline fragment (Fc) receptors for IgE on their mast cells. Greater quantities of histamine, more histamine receptors, and a deficiency in epinephrine do not lead to a genetic predisposition to allergies.
28. How many months does it take for the newborn to be sufficiently protected by antibodies produced by its own B cells? a. 1 to 2 b. 4 to 5 c. 6 to 8 d. 10 to 12
ANS: C By 6 to 8 months, the newborn should be efficiently protected by antibodies produced by its own B cells.
17. In a type III hypersensitivity reaction, the harmful effects after the immune complexes that are deposited in tissues are a result of what? a. Cytotoxic T cells b. Natural killer cells c. Complement activation d. Degranulation of mast cells
ANS: C Complement activation, particularly through the generation of chemotactic factors for neutrophils, causes the harmful effects of immune complex deposition. The neutrophils bind to antibody and C3b contained in the complexes and attempt to ingest the immune complexes. Type III hypersensitivity reactions as described are not the result of cytotoxic T cells, natural killer cells, or degranulation of mast cells.
6. During an IgE-mediated hypersensitivity reaction, what causes bronchospasm? a. Bronchial edema caused by the chemotactic factor of anaphylaxis b. Bronchial edema caused by binding of the cytotropic antibody c. Smooth muscle contraction caused by histamine bound to H1 receptors d. Smooth muscle contraction caused by histamine bound to H2 receptors
ANS: C During an IgE-mediated hypersensitivity reaction, smooth muscle contraction caused by histamine bound to H1 receptors results in bronchospasms. The bronchospasm is not caused by edema or by histamine binding to H2 receptors.
1. How is hypersensitivity best defined? a. A disturbance in the immunologic tolerance of self-antigens b. An immunologic reaction of one person to the tissue of another person c. An altered immunologic response to an antigen that results in disease d. An undetectable immune response in the presence of antigens
ANS: C Hypersensitivity is an altered immunologic response to an antigen that results in disease or damage to the host. Autoimmunity is a disturbance in the immunologic tolerance of self-antigens. Alloimmunity is the immunologic reaction of one person to the tissue of another person. An immune deficiency of some type would cause undetectable immune response in the presence of antigens.
31. What is Graves disease a result of? a. Increased levels of circulating immunoglobulins b. The infiltration of the thyroid with T lymphocytes c. Autoantibodies binding to thyroid-stimulating hormone (TSH)-receptor sites d. Exposure to acetylates in substances such as rubber
ANS: C In the hyperthyroidism (excessive thyroid activity) of Graves disease, autoantibody binds to and activates receptors for TSH (a pituitary hormone that controls the production of the hormone thyroxine by the thyroid). Graves disease is not caused by increased levels of circulating immunoglobulins, infiltration of the thyroid by T lymphocytes, or by exposure to acetylates.
5. During an IgE-mediated hypersensitivity reaction, which leukocyte is activated? a. Neutrophils b. Monocytes c. Eosinophils d. T lymphocytes
ANS: C Of the options provided, only eosinophils are activated during IgE-mediated hypersensitivity reactions.
21. Tissue damage caused by the deposition of circulating immune complexes containing an antibody against the host DNA is the cause of which disease? a. Hemolytic anemia b. Pernicious anemia c. Systemic lupus erythematosus d. Myasthenia gravis
ANS: C The deposition of circulating immune complexes containing an antibody against the host DNA produces tissue damage in individuals with systemic lupus erythematosus (SLE). That is not a process in hemolytic anemia, pernicious anemia, or myasthenia gravis.
16. A type IV hypersensitivity reaction causes which result? a. Antibodies coating mast cells by binding to receptors that signal its degranulation, followed by the discharge of preformed mediators b. Antibodies binding to soluble antigens that were released into body fluids and the immune complexes being deposited in the tissues c. Lymphokine-producing Th1 cells directly attacking and destroying cellular targets d. Antibodies binding to the antigen on the cell surface
ANS: C Type I, II, and III hypersensitivity reactions are mediated by antibody, type IV reactions are mediated by T lymphocytes and do not involve antibody. Type IV mechanisms occur through either Tc cells or lymphokine-producing Th1 cells. Tc cells directly attack and destroy cellular targets.
25. Which class of immunoglobulins forms isohemagglutinins? a. IgA b. IgE c. IgG d. IgM
ANS: D Naturally occurring antibodies, called isohemagglutinins, are immunoglobulins of only the IgM class.
26. Which component of the immune system is deficient in individuals with infections caused by viruses, fungi, or yeast? a. Natural killer cells b. Macrophages c. B cells d. T cells
ANS: D Of the available options, deficiencies in T-cell immune responses are suggested when certain viruses (e.g., varicella, vaccinia, herpes, cytomegalovirus), fungi, and yeasts (e.g., Candida, Histoplasma) or certain atypical microorganisms (e.g., Pneumocystis jiroveci) cause recurrent infections.
12. When soluble antigens from infectious agents enter circulation, what is tissue damage a result of? a. Complement-mediated cell lysis b. Phagocytosis by macrophages c. Phagocytosis in the spleen d. Neutrophil granules and toxic oxygen products
ANS: D Of the options available, only the components of neutrophil granules as well as the several toxic oxygen products produced by these cells, damage the tissue.
9. A student asks about the mechanism that results in type II hypersensitivity reactions. What description by the professor is best? a. Antibodies coat mast cells by binding to receptors that signal its degranulation, followed by a discharge of preformed mediators. b. Antibodies bind to soluble antigens that were released into body fluids, and the immune complexes are then deposited in the tissues. c. Cytotoxic T lymphocytes or lymphokine-producing helper T 1 cells directly attack and destroy cellular targets. d. Antibodies bind to the antigens on the cell surface.
ANS: D The mechanism that results in a type II hypersensitivity reaction begins with antibody binding to tissue-specific antigens or antigens that have attached to particular tissues. The cell can be destroyed by antibody IgG or IgM and activation of the complement cascade through the classical pathway.
13. How are target cells destroyed in a type II hypersensitivity reaction? a. Tissue damage from mast cell degranulation b. Antigen-antibody complexes deposited in vessel walls c. Cytotoxic T lymphocytes attack the cell directly. d. Natural killer cells
ANS: D The mechanism that results in a type II hypersensitivity reaction involves a subpopulation of cytotoxic cells that are not antigen specific (natural killer [NK] cells). Antibody on the target cell is recognized by Fc receptors on the NK cells, which releases toxic substances that destroy the target cell. Tissue damage from mast cell degranulation occurs in type I hypersensitivity reactions. Antigen-antibody complexes are active in type III hypersensitivity responses. Cytotoxic lymphocytes are involved in type IV hypersensitivity responses.
23. Which blood cell carries the carbohydrate antigens for blood type? a. Platelets b. Neutrophils c. Lymphocytes d. Erythrocytes
ANS: D The reaction that causes a blood transfusion recipient's red blood cells to clump together is related to the ABO antigens located on the surface of only erythrocytes.
24. A person with type O blood needs a blood transfusion. What blood type does the healthcare professional prepare to administer to the patient? a. A b. B c. AB d. O
ANS: D Type O individuals have neither A or B antigen but have both anti-A and anti-B antibodies and therefore cannot accept blood from any of the other three types. The healthcare professional would prepare to administer a transfusion of type O blood.
30. Urticaria is a manifestation of a which type of hypersensitivity reaction? a. IV b. III c. II d. I
ANS: D Urticaria, or hives, is a dermal (skin) manifestation of only type I allergic reactions.
Which is an example of an alloimmune disease? a. Tuberculin reaction b. Graves disease c. Contact dermatitis d. Penicillin allergy
B Graves disease is a classic autoimmune, or alloimmune, disease. Tuberculin reaction is a type IV reaction. Contact dermatitis is a type I reaction. Penicillin is an allergen that induces type I hypersensitivity.
Which statement best describes a type I reaction? a. Most type I reactions are mediated by IgA. b. Most type I reactions are allergic. c. Most occur against medications. d. Rarely does this type of reaction contribute to autoimmune diseases.
B Most type I reactions are allergic. They are mediated by IgE. Most type I reactions occur against environmental antigens and can contribute to some autoimmune diseases.
Which statement is true regarding atopic individuals? a. If one parent has allergies, then a 4% chance exists that the offspring will have similar allergies. b. If two parents have allergies, then a 50% chance exists that their offspring will have similar allergies. c. Atopic individuals tend to produce higher quantities of IgE. d. No genes are associated with an atopic state.
C Higher quantities of IgE are present in atopic individuals. If one parent has an allergy, then the individual has a 40% of having allergies; with two parents, the individual has an 80% of having allergies. Multiple genes have been associated with the atopic state.
The Arthus reaction is an example of which type of sensitivity reaction? a. I b. II c. III d. IV
C The Arthus reaction is a type III hypersensitivity reaction.
Which statement is true regarding unmatched packed red blood cell (RBC) transfusions? a. Only three different RBC antigens have been identified. b. Approximately 80 major carbohydrate antigens exist. c. People with O type blood have neither A or B antigens. d. A person with type A blood contains anti-O antibodies.
C Type O blood does not contain type A or B antigens. However, 80 major different RBC antigens are present. A person with type A blood carries anti-B antibodies and a person with type B blood carries anti-A antibodies. Those with type O blood have anti-A and anti-B antibodies.
Which statement is true regarding a type IV allergic reaction? a. Is immediate in its action b. Is infiltrated with B cells c. Is mediated by antibody production d. Can be transferred by cells
D Type IV hypersensitivity reactions can be transferred by cells but not by serum. Their actions are delayed because their onset takes from 24 to 72 hours. The site is infiltrated with T lymphocytes and macrophages. A clear hard center surrounds the erythema (redness).