Chapter 18: AIDS and Other Immune Disorders

**Describe how an immunodeficiency disease is different from an autoimmune disease.

"Autoimmune diseases are caused by overactive immune system leading to damage of self-tissues and organs in the absence of a harmful stimulus. Immune deficiency is a disease where the immune system is not capable of mounting an immune response against foreign material"(difference between.com).

**Describe the cause of graft rejection.

"The person's immune system detects that the antigens on the cells of the organ are different or not "matched." Mismatched organs, or organs that are not matched closely enough, can trigger a blood transfusion reaction or transplant rejection"(Medline plus).

**For each blood type be sure to understand what antigens and antibodies are present as well as what blood type a person with that blood type might safely receive blood from and donate blood to.

ABO blood group A has A antigens present, B antibodies present, can donate to A or AB, and can receive A and O. ABO blood group B has B antigens present, A antibodies present, can donate to B or AB, and can receive from B or O. ABO blood group AB has A and B antigens, no antibodies present, can donate to AB, and can receive from A, B, AB, or O (universal recipient). ABO blood group O has no antigens present, A and B antibodies present, can donate to A, B, AB, or O (universal donor), and can receive from O.

**Identify the difference between autograft, isograft, allograft, and xenograft. Be able to give or recognize examples of each.

Autograft-made between different sites within a single individual. Example: the grafting of skin from your own body; from leg to arm. Isograft-between genetically identical individuals. Example: Identical twin donates a kidney. Allograft-between genetically dissimilar individuals. Example: Person receives a heart from a cadaver. Xenograft-between individuals of different species. Example: Pig heart valves placed in a human.

**Describe the ABO system and transfusion reactions.

Blood group antigens are surface molecules of RBC's. Each persons RBC's have A antigen, B antigen, both antigens, or neither antigen. A transfusion reaction can result if an individual receives a different blood type. Donors blood group antigens may stimulate the production of antibodies in the recipient that destroy the transfused cells. If the recipient has pre-existing antibodies to the foreign blood group antigens, immediate destruction of donated blood cells can occur. If the recipient has no preexisting antibodies to foreign blood group antigens then transfused cells initially circulate and function normally, eventually, the recipient's immune system mounts a primary response against the foreign antigens and destroys them.

**Describe HIV (include structure and origin of virus) and how it replicates.

HIV is a severe decrease in the number of CD4+ cells and a positive test showing the presence of antibodies against HIV. The structure is a typical retrovirus in shape, components, and size, 2 glycoproteins characterize its envelope. Evidence suggests that HIV arose from mutation of a similar virus-simian immunodeficiency virus-found in African monkeys, chimpanzees, and other simians. HIV replicates by attaching to four kinds of cells (helper T cells, macrophages, and dendritic cells). Using gp 120, HIV fuses to a cell, uncoats, enters the cell, and transcribes dsDNA to become provirus. The viral enzyme integrase inserts the provirus into a human chromosome.

**Identify which immunoglobulins are involved in this type of reaction. Explain what is happening on a cellular level to cause symptoms.

IgG and IgM are the immunoglobulins involved in immune complex-mediated hypersensitivity. This reaction "occurs when there is accumulation of immune complexes (antigen-antibody complexes) that have not been adequately cleared by innate immune cells, giving rise to an inflammatory response and attraction of leukocytes"(Wikipedia).

**Identify the similarities and differences between hypersensitivities, autoimmune diseases, and immunodeficiency diseases.

Immunodeficiency can be genetic, or acquired from a disease, pathogen or drug. It impairs the function and production of immune cells, making the patient very susceptible to disease and infections. Hypersensitivity is when the immune system is hyperactive to normally harmless antigens like dust, pollen, and animal allergies. Autoimmune disorders make the body's immune system unable to distinguish between its own antigens and foreign antigens. It destroys its own cells.

**Describe the concept and result of autoimmune diseases and autoimmunity. Describe how these diseases are related to hypersensitivity.

Results when an individual begins to make autoantibodies or cytotoxic T cells against normal body components. Autoimmune diseases are related to hypersensitivity because "many autoimmune diseases have a hypersensitivity reaction as part (or all) of their pathogenesis"(pathology student.com).

**Be sure to understand what child blood types are possible from the different possible combinations of parental blood type.

Since there are 4 different maternal blood types and 4 different paternal blood types possible, there are 16 differnt combinations to consider when predicting the blood type of children. In the tables below, all 16 possible combinations are shown. If you know the blood type of the mother and father, the possible blood types for their children can be found. see homework 15 for chart

**Identify why Type I hypersensitivity is called immediate sensitivity, how this relates to allergies, and what allergens are. Identify some common allergens.

Type 1 hypersensitivity is called immediate because it develops within seconds or minutes following exposure to an antigen. This relates to allergies because the antigens that stimulate it are called "allergens." Allergens are the antigens that trigger allergies. Some common allergens are ragweed, dust mites, fungal (mold)spores, pollens from grasses, flowering plants, and some trees.