Immunology
Treating IgG with pepsin causes production of heavy and light chains epitopes the hinge region (Fab')2 +Fc fragments 2 Fab and an Fc
(Fab')2 +Fc fragments
Refer to the following illustration: Which of the above figures demonstrates a reaction pattern of identity? 1 2 3 4
1
A series of 8 tubes are set-up with 0.79 ml of diluent in each. A serial dilution is performed by adding 10 ul of serum to the first tube and then transferring 10 ul through each remaining tube. What is the serum dilution of tube 7? 1:2.43 x 10 ^11 1:2.621 x 10 ^11 1:1.920 x 10 ^ 13 1:2.097 x 10 ^1 3
1:2.097 x 10 ^1 3
Refer to the following illustration: Which of the above figures demonstrates a reaction pattern of non-identity? 1 2 3 4
2
The National Fire Protection Association Diamond has 4 parts: flammability, reactivity, special risks, and health risks 5 parts: flammability, reactivity, special and health risks, and infectivity 3 parts: flammability, reactivity, and health risks 2 parts: explosion risk and infection risk
4 parts: flammability, reactivity, special risks, and health risks
What percentage of the SLE patients is positive for antinuclear antibodies
95
The zeta potential is the charge on particles that complicates agglutination reaction a charge that can be decreased with low ionic strength saline a charge that is increased with low ionic strength saline A and B
A and B
What substance is detected by the rapid plasma reagin (RPR) and Venereal Disease Research Laboratory (VDRL) tests for syphilis?
Anticardiolipin antibody
Which of the following is involved in a humoral immune response? macrophage T cells NK cells neutrophil B lymphocyte
B lymphocyte
Which of the following is involved in a humoral immune response? neutrophil B lymphocyte macrophage NK cells
B lymphocyte
Which of the following would have HEPA filtered air blowing into the hood? A.) a chemical containment hood B.) a biological containment hood both A and B none of the above
B.) a biological containment hood
What is the most likely interpretation of the following syphilis serological results? RPR: reactive; VDRL: reactive; MHA-TP: nonreactive.
Biological false positive
An acute phase reactant involved in cardiac risk measurements is(are) unmethylated DNA, ss RNA defensins and cathelicidins C-reactive protein SALT
C-reactive protein
Which complement component requires CA ions to stay together? C4 C3 C2 C1
C1
The correct order for the classical complement pathway is: C1, C4, C3, C4, C5, C6, C7, C8, C9 C1, C2, C4, C5, C4, C6, C7, C8, C9 C1, C4, C2, C3, C5, C6, C7, C8, C9 C1, C2, C3, C4, C5, C6, C7, C8, C9
C1, C4, C2, C3, C5, C6, C7, C8, C9
Which of the following is the worst clinical deficiency to have? C1 C2 C9 C3
C3
Which complement component is found in both the classic and alternative pathways? C3 C1 Factor D C4 C3 is found in both the classic and alternative (alternate) pathways of the complement system. In the classic pathway, C3b forms a complex on the cell with C4b2a that enzymatically cleaves C5. In the alternative pathway, C3b binds to an activator on the cell surface. It forms a complex with factor B called C3bBb which, like C4b2a3b, can split C5.
C3 C3 is found in both the classic and alternative (alternate) pathways of the complement system. In the classic pathway, C3b forms a complex on the cell with C4b2a that enzymatically cleaves C5. In the alternative pathway, C3b binds to an activator on the cell surface. It forms a complex with factor B called C3bBb which, like C4b2a3b, can split C5.
The alternative pathway for activation needs which of the following? C1-9 and factor B, properdin, factor I and factor H C3, Properdin, factor B, factor D, initiating factor (IF) lipids All of the above
C3, Properdin, factor B, factor D, initiating factor (IF)
Which specimen is the sample of choice to evaluate latent or tertiary syphilis?
CSF
What type of antigen is used in the RPR card test?
Cardiolipin
Another student has an odd-looking blistery rash and has been losing weight. You and she are good friends, but must she tell you about her bowel symptoms? She has diarrhea and cramping. What do you think she might have? Grave's disease Hashimoto's disease Addison's disease Celiac disease
Celiac disease
Antibodies against the yeast species Saccharomyces cervesiae are found in which of the following diseases? celiac Crohn's autoimmune hepatitis Addison's
Crohn's
Which serum antibody response usually characterizes the primary (early) stage of syphilis?
Detected 1-3 weeks after appearance of the primary chancre
When we ran the serum of a patient who seems to be severely ill with arthritis at the lowest dilution suggested by the latex agglutination kit, the results were negative. What should we do? Report the results to the physician and suggest the patient return in two weeks when his titer might be higher. Report the results to the physician and suggest testing for Lyme disease. Dilute the sample and run it again before the results are reported. Use a different company's kit.
Dilute the sample and run it again before the results are reported.
What is an SDS? A.) a document that contains the reactivity and toxicity information about a material B.) a document that contains the proper first aid in case of exposure to a chemical C.) a document that shows where the safety material in the lab is D.) all of the above E.) A and B
E.) A and B
Which test has the greatest sensitivity for antigen detection? precipitin agglutination ELISA complement fixation
ELISA
Interpret the following quantitative RPR test results. RPR titer: weakly reactive 1:8; reactive 1:8-1:64
Excess antibody, prozone effect
Which test is most likely to be positive in the tertiary stage of syphilis?
FTA-ABS
Which region of the immunoglobulin molecule can bind antigen? CL Fc CH Fab
Fab The Fab (fragment antigen binding) is the region of the immunoglobulin molecule that can bind antigen. Two Fab fragments are formed from hydrolysis of the immunoglobulin molecule by papain. Each consists of a light chain and the VH and CH1 regions of the heavy chain. The variable regions of the light and heavy chains interact, forming a specific antigen-combining site.
In testing for DiGeorge's syndrome, what type of laboratory analysis would be most helpful in determining the number of mature T cells?
Flow cytometry
A biological false-positive reaction is least likely with which test for syphilis?
Fluorescent T. pallidumantibody absorption test (FTA-ABS)
A student in the class always is complaining that she's cold, she's tired, she's been gaining weight but says she just doesn't care about anything anymore. The semester has been tough, and although you feel guilty, at first you ignore her, but just now as you looked up, her neck appears to be enlarged in the front and her skin and hair look dry. What do you think she might have? Grave's disease Hashimoto's disease Addison's disease Celiac disease
Hashimoto's disease
Of two different autoimmune diseases of the thyroid gland occur that give different symptoms, which of the following is consistent with the symptoms seem in each disease? Hashimoto's diseases: is hot, needs little sleep, has dry skin, has lost weight; Grave's: is cold, is tired, has gained weight Hashimoto's disease: is cold, needs little sleep, has dry skin, has gained weight; Grave's: is hot, is tired, has lost weight Hashimoto's diseases: is cold, is tired, has dry skin, has gained weight; Grave's: is hot, needs little sleep, has lost weight Hashimoto's diseases: is hot, needs little sleep, has dry skin, has lost weight; Grave's: is cold, is tired, has gained weight
Hashimoto's diseases: is cold, is tired, has dry skin, has gained weight; Grave's: is hot, needs little sleep, has lost weight
How is complement activity destroyed in vitro? Keeping serum at room temperature of 22°C for 1 hour Freezing serum at 0°C for 24 hours Heating serum at 37°C for 45 min Heating serum at 56°C for 30 min Complement activity in serum in vitro is destroyed by heating the serum at 56°C for 30 min. In test procedures where complement may interfere with the test system, it may be necessary to destroy complement activity in the test sample by heat inactivation.
Heating serum at 56°C for 30 min Complement activity in serum in vitro is destroyed by heating the serum at 56°C for 30 min. In test procedures where complement may interfere with the test system, it may be necessary to destroy complement activity in the test sample by heat inactivation.
One of the immunoglobulin molecules found as a dimer in secretions is IgG IgD IgE IgA IgM
IgA
The antibody that is protective in serum, is made after IgM, and does not cause allergy is IgA IgG IgD IgM IgE
IgG
Which immunoglobulin(s) help(s) initiate the classic complement pathway? IgM only IgG and IgM IgA and IgD IgG only
IgG and IgM Both IgG and IgM are the immunoglobulins that help to initiate the activation of the classic complement pathway. IgM is a more potent complement activator, however.
In the latex agglutination assay for rheumatoid factor, the antigen coated on the latex beads is CCP IgG with the Fc facing in IgG with the Fc facing out CCP and IgG with the Fc facing out
IgG with the Fc facing out
The antibody molecule that has 10 binding sites but because of steric hinderance often binds only five antigen molecules is IgE IgD IgM IgA IgG
IgM
Which immunoglobulin class(es) has (have) a J chain? IgM and IgA IgM IgE and IgD IgG3 and IgA
IgM and IgA Both IgM and secretory IgA have a J chain joining individual molecules together; the J chain in IgM joins five molecules and the J chain in sIgA joins two molecules.
From the following, identify a specific component of the adaptive immune system that is formed in response to antigenic stimulation: Lysozyme Complement Commensal organisms Immunoglobulin
Immunoglobulin
From the following, identify a specific component of the adaptive immune system that is formed in response to antigenic stimulation: Commensal organisms Immunoglobulin Lysozyme Complement
Immunoglobulin Immunoglobulin is a specific part of the adaptive immune system and is formed only in response to a specific antigenic stimulation. Complement, lysozyme, and commensal organisms all act nonspecifically as a part of the adaptive immune system. These three components do not require any type of specific antigenic stimulation.
All of the following are immunologic functions of complement except: Anaphylatoxin formation Opsonization Induction of an antiviral state Chemotaxis
Induction of an antiviral state Complement components are serum proteins that function in opsonization, chemotaxis, and anaphylatoxin formation but do not induce an antiviral state in target cells. This function is performed by interferons.
Regarding the affinity of antibody to antigen, Ka = [Ab][Ag]/[AbAg] Ka = [AbAg]/[Ab][Ag] Kd = [Ab][Ag]/[AgAb] none of the above
Ka = [AbAg]/[Ab][Ag]
A phagocytic cell is a(n) Platelet T or B lymphocyte Macrophage NK cell
Macrophage
T cells travel from the bone marrow to the thymus for maturation. What is the correct order of the maturation sequence for T cells in the thymus? Storage in either the cortex or medulla; release of T cells into the peripheral circulation Maturation and selection occur in the cortex; migration to the medulla; release of mature T cells to secondary lymphoid organs Activation and selection occur in the medulla; mature T cells are stored in the cortex until activated by antigen Bone marrow to the cortex; after thymic education, released back to peripheral circulation
Maturation and selection occur in the cortex; migration to the medulla; release of mature T cells to secondary lymphoid organs Activation and selection occur in the medulla; mature T cells are stored in the cortex until activated by antigen Immature T cells travel from the bone marrow to the thymus to mature into functional T cells. Once in the thymus, T cells undergo a selection and maturation sequence that begins in the cortex and moves to the medulla of the thymus. Thymic factors such as thymosin and thymopoietin and cells within the thymus such as macrophages and dendritic cells assist in this sequence. After completion of the maturation cycle, T cells are released to secondary lymphoid organs to await antigen recognition and activation.
A lymphocyte in the innate system is called mast cell T cell B cell NK cell
NK cell
Which of the following cells kills tumor cells and virally infected cells, not antigen specific, uses perforins neutrophil B lymphocyte macrophage NK cells
NK cells
What type of B cells are formed after antigen stimulation? Plasma cells and memory B cells Mature B cells Antigen-dependent B cells Receptor-activated B cells
Plasma cells and memory B cells
Which of the following is the most sensitive test to detect congenital syphilis?
Polymerase chain reaction (PCR)
Which of the following is not a functional assay for complement? Radial immunodiffusion none of the above CH50 AH50
Radial immunodiffusion
An antinuclear antibody test is performed on a specimen from a 55-year-old woman who has unexplained joint pain. The IFA result is a titer of 40 and a homogeneous pattern. The appropriate follow-up for this patient is:
Retest ANA in 3-6 months
Dry eyes and mouth are symptoms of which of the following diseases? scleroderma myasthenia gravis Sjögren's syndrome systemic sclerosis
Sjögren's syndrome
Which disease is likely to show a rim (peripheral) pattern in an immunofluorescence (IF) microscopy test for ANA?
Systemic lupus erythematosus
An antigen-specific cell is a neutrophil T or B lymphocyte macrophage NKcell
T or B lymphocyte
Specific treponemal Ags used to detect Ab-antigen T.pallidum are in which of the following assays
TPHA
Which two organs are considered the primary lymphoid organs in which immunocompetent cells originate and mature? Thyroid and Peyer's patches Thymus and bone marrow Spleen and mucosal-associated lymphoid tissue (MALT) Lymph nodes and thoracic duct
Thymus and bone marrow
What is the purpose of C3a, C4a, and C5a, the split products of the complement cascade? To regulate and degrade membrane cofactor protein after activation by C3 convertase To bind with membrane receptors of macrophages to facilitate phagocytosis and the removal of debris and foreign substances To bind with specific membrane receptors of lymphocytes and cause release of cytotoxic substances To cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils
To cause increased vascular permeability, contraction of smooth muscle, and release of histamine from basophils C3a, C4a, and C5a are split products of the complement cascade that participate in various biological functions such as vasodilation and smooth muscle contraction. These small peptides act as anaphylatoxins, e.g., effector molecules that participate in the inflammatory response to assist in the destruction and clearance of foreign antigens.
A 12-year old girl has symptoms of fatigue and a localized lymphadenopathy. Laboratory tests reveal a peripheral blood lymphocytosis, a positive RPR, and a positive spot test for IM. What test should be performed next?
Treponema pallidum particle agglutination (TP-PA) test
Syphilis is detected first by a(n) _________ or a(n)_________ and then if that is positive by __________ or _____________.
VDRL, RPR, FTA-ABS, microhemagglutination after absorption
The curve below was obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum: The area on the curve for prozone is: a b c d
a
To determine whether a patient has autoimmune hemolytic anemia, we can add anti-human immunoglobulin to the person's red blood cells, which is a reverse passive test a competitive assay an indirect antiglobulin test a direct antiglobulin test
a direct antiglobulin test
The secondary stage of syphilis is characterized by
a rash
Autoimmunity involves genetics can sometimes be gender associated can be hormone associated all of the above
all of the above
Autoimmunity can be infection associated because of a cross-reactive epitope environmentally associated trauma associated all of the above
all of the above
C5a can cause vasodilation smooth muscle contraction all of the above chemotaxis
all of the above
The best way to prevent blood exposure is to wear gloves be familiar with the safety equipment and use it wear a buttoned lab coat that goes past your knees use eye and face protection all of the above
all of the above
The primary stage of syphilis occurs after sexual contact with a person with primary or secondary lesions occurs after the organism enters through a small break in the skin usually presents with a lesion called a chancre all of the above
all of the above
Which of the following is used for testing the specificity of the antibody in a patient suspected of having SLE? ANA testing on HEP-2 cells ELISA testing testing on Crithidia luciliae all of the above
all of the above
Nephelometry and turbidimetry differ because although both measure the effect of aggregates on light passing through a solution, turbidimetry measures the light scattered at 10-90°, and nephelometry measures the light that goes directly through the solution although both measure the effect of aggregates on light passing through a solution, turbidimetry measures the light scattered at 10-90°, and nephelometry measures the light that is polarized nephelometry uses instrumentation but turbidimetry does not although both measure the effect of aggregates on light passing through a solution, nephelometry measures the light scattered at 10-90°, and turbidimetry measures the light that goes directly through the solution
although both measure the effect of aggregates on light passing through a solution, nephelometry measures the light scattered at 10-90°, and turbidimetry measures the light that goes directly through the solution
The best method to detect infections due to rubella, Ebstein-Barr and human immunodeficiency viruses is: antigen detection by EIA cell culture antigen detection by Western blot antibody detection by EIA
antibody detection by EIA
Immunoassays are based on the principle of separation of bound and free analyte antibody recognition of homologous antigen protein binding to isotopes production of antibodies against drugs
antibody recognition of homologous antigen
What should you look for to determine the diagnosis of Grave's disease? IgA against tissue transglutaminase autoantibodies targeting the adrenal cortex antibody to thyroid hormone-stimulating receptor, thyroxine (T3 and T4) levels thyroxine (T3 and T 4) levels and antibodies to thyroglobulin and thyroperoxidase
antibody to thyroid hormone-stimulating receptor, thyroxine (T3 and T4) levels
Equivalence occurs when the antibody-binding sites approximately equal the antigen-binding sites, and the largest complexes form antibody-binding sites approximately equal twice the antigen-binding sites, and the largest complexes form postzone has been passed, more antigen has been added, and the largest complexes form prozone has been passed, more antibody has been added, and the largest complexes form
antibody-binding sites approximately equal the antigen-binding sites, and the largest complexes form
Soluble immune complexes are formed under the condition of: antigen deficiency antigen excess antibody excess complement
antigen excess
Ka the number of binding sites = the affinity avidity molecular weight turbidimetry number
avidity
The strength of a visible reaction is known as: prozone reaction absorption avidity elution
avidity
The curve below was obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum: The area on the curve where no precipitate formed due to antigen excess is a b c d
b
The curve below was obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum: The area on which the addition of more antibody would result in the formation of additional precipitate is: a b c d
b
Agglutination is less sensitive than precipitation more sensitive than precipitation if the particles are highly charged better with IgM at lower temperatures (4-27°) called passive agglutination when the antigen is naturally part of the particle
better with IgM at lower temperatures (4-27°)
Match the following terms: binds to mast cells IgE first antibody produced IgM highest in serum concentration IgG highest in secretions IgA
binds to mast cells IgE first antibody produced IgM highest in serum concentration IgG highest in secretions IgA
C1q can interact with? a) IgM both a and c b) IgA c) IgG
both a and c (IgM+IgG)
The curve below was obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum: The area on the curve for equivalence precipitate is: a d c b
c
IgA autoantibodies against gliadin, tissue transglutaminase, and endomysium are found in patients which of the following diseases? celiac Crohn's type 1 diabetes mellitus Addison's
celiac
The curve below was obtained by adding increasing amounts of a soluble antigen to fixed volumes of monospecific antiserum: The area on the curve where soluble antigen-antibody complexes have begun to form is: a b c d
d
SLE is a. related to a single gene mutation b. made worse by exposure to sunlight c. due to inflammation caused by circulating immune complexes d. B and C
d. B and C
Which cell is very active in antigen presentation? LAK cells dendritic cells epithelial cells T cells
dendritic cells
Which of the following diseases is strongly related to celiac disease? pemphigus vulgarus dermatitis herpetiformis bullous pemphigoid basal cell carcinoma
dermatitis herpetiformis
The process by which macrophage and neutrophils squeeze through the intact blood vessel is opsonization diapedesis chemotaxis phagocytosis
diapedesis
Excess antigen in precipitation gel reactions will: have no effect on the precipitate reaction not dissolve precipitate after formation enhance the precipitate reaction dissolve the precipitate after formation
dissolve the precipitate after formation
The serological test that can be modified to selectively detect only specific IgM antibody in untreated serum is: Ouchterlony enzyme immunoassay hemoagglutination in hibition passive hemagglutination
enzyme immunoassay
A heterophile antigen is best described as?
existing in an unrelated animal
Precipitin reactions are still used clinically for bacterial infections fungal infections cancer viral infections
fungal infections
MALT relates to the area on an immunoglobulin molecule defined by structure amino terminus of the antibody molecule that contains the paratope gastrointestinal and respiratory tract lymphoid tissue spleen, lymph node, and tonsil
gastrointestinal and respiratory tract lymphoid tissue
How should the patient with Hashimoto's disease be treated? placed on a gluten-free diet given thyroid hormone replacement therapy treat the symptoms, which sometimes resolves the situation given replacement therapy with glucocorticoids and mineralocorticoids
given thyroid hormone replacement therapy
Denaturing and breaking disulfide bonds gives the hinge regions heavy and light chains 2 Fab and an Fc (Fab')2 +Fc fragments
heavy and light chains
OSHA requires that employers offer which of these vaccines to hospital employees who may be at risk for hepatitis A hepatitis B hepatitis C HIV
hepatitis B
What bloodborne virus can survive on surfaces for more than 1 week? hepatitis C hepatitis B HIV all of the above.
hepatitis B
What is the immunologic method utilized in the flow cytometer? latex agglutination enzyme linked immunoassay immunoflorescence radioimmunoassay
immunoflorescence
The cell of the following cell types that is called a Kupfer cell when in the liver is neutrophil T or B lymphocyte macrophage NK cell
macrophage
The phagocytic cell that does not arrive first at the site of a chronic infection is the neutrophils B cells macrophages NK cells
macrophages
A lymphocyte has more cytoplasm than nucleus equal amounts of cytoplasm and nucleus more nucleus than cytoplasm segmented nucleus
more nucleus than cytoplasm
Antibody-mediated destruction of the acetylcholine receptor at the postsynaptic membrane of the neuromuscular junction occurs in which of the following diseases? multiple sclerosis Addison's biliary cirrhosis myasthenia gravis
myasthenia gravis
The first cell at the site of an infection is a(n) neutrophil T or B Lymphocyte macrophage NK cell
neutrophil
Which of the following has a polymorphic nucleus neutrophil B lymphocyte macrophage NK cells T cells
neutrophil
Natural or innate immunity is specific immunity non-specific immunity immunoglobulin cytotoxic T cells
non-specific immunity
When does neurosyphilis commonly occur? when someone with HIV becomes infected with Treponema pallidum Bin most cases of syphilis from a cut in the skin none of the above
none of the above
Epitopes are the outermost part of a carbohydrate part of the antibody molecule that binds to the antigen outermost part of the protein part of the antigen that binds to the binding site of the antibody
part of the antigen that binds to the binding site of the antibody
When a phagocytic cell engulfs a bacteria, the bacteria is in the cellular compartment known as lysosome chemotaxin opsonin phagosome
phagosome
he following cold agglutinin titer results are observed: The best interpretation is: tube # 1 2 3 4 5 6 7 8 9 10 dilution 1:1 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 1:512 4C + + + + + + + + 0 0 37 C 0 0 0 0 0 0 0 0 0 0 negative positive, 1:128 invalide because 37 C readings are negative reapeat the 4 C readings
positive, 1:128
The visible serological reaction between soluble antigen and its specific antibody is: sensitization precipitation agglutination opsonization
precipitation
Which of the following describes an antigen-antibody precipitation reaction of non-identity? precipitin lines cross, forming double spurs precipitin lines fuse, forming a single spur no precipitin lines are formed precipitin lines fuse, forming a single arc
precipitin lines cross, forming double spurs
What is the most common way for needlestick accidents to occur? drawing blood from a child drawing blood from a prisoner recapping a needle disposing of trash from a hospital laboratory
recapping a needle
Which of the following is not a major symptom of tertiary syphilis?
respiratory disease
Antibody to cyclic citrullinated peptide (CCP) is diagnostic for SLE rheumatoid arthritis Sjögren's syndrome mixed connective tissue disease
rheumatoid arthritis
Compared to a secondary response, a primary response is slower and lower in amount of IgG slower but higher in amount of IgG faster and higher in amount of IgG faster, more specific but lower in amount of IgG
slower and lower in amount of IgG
Avidity may be defined as the: degree of hemolysis titer of an antigen dilution of an antibody strength of a reacting antibody
strength of a reacting antibody
In congenital syphilis
the baby can show a rash, neurosyphilis and / or anemia
Apoptosis, also known as programmed cell death occurs when the cell receives certain signals and then sends perforins to kill neighboring cells the cell receives certain signals and digests its own DNA the cell receives certain signals and digests its own membrane none of the above
the cell receives certain signals and digests its own DNA
A secondary lymphoid organ is TLR bacterial Flagellin tonsils C-reactive protein (CRP)
tonsils
What should you test to determine the diagnosis of Hashimoto's disease? IgA against tissue transglutaminase autoantibodies targeting the adrenal cortex antibody to thyroid hormone-stimulating receptor, triiodothyronine and thyroxine (T3 and T4), levels triiodothyronine and thyroxine (T3 and T 4) levels and antibodies to thyroglobulin and thyroperoxidase
triiodothyronine and thyroxine (T3 and T 4) levels and antibodies to thyroglobulin and thyroperoxidase
Antibodies to glutamic acid decarboxylase-65, insulin-associated antigen, and insulin found are found in which of the following diseases? Celiac Crohn's type 1 diabetes mellitus Addison's
type 1 diabetes mellitus
Shyphilis is
usually treatable with penicillin