Immune System (ASCPi)

• CD16

• CD56

CD markers of natural killer cells

Cytokines

Polypeptide products of activated cells that control a variety of cellular response and thereby regulate the immune response

CD19

Panmarker of B-cells

CD20

It acts as an ion channel for B-cells

CD21

It serves as a C3d receptor for B-cells (also EBV receptor)

CD2

It is a classic T-cell marker and sheep RBC receptor

Flow cytometry

Uses light scattering and fluorescent antibodies to detect antigen

Ficoll-Hypaque centrifugation

Technique which separates lymphocytes from whole blood

Th helper

It enhances the activity of cytotoxic cells

500-1200/uL

What is the normal CD4 count range?

2:1

CD4+ cells to CD8+ cells ratio:

1:2 to 0.5:1

Ratio of CD4+ cells to CD8+ cells in HIV:

<200/uL

AIDS CD4+ cell count:

Plasma cell

Antibody producing cell; derived from B cells

Th1

Which T-helper cell produces IFN-y and induces Type IV hypersensitivity reactions?

Th2

Which T-helper cell produces IL-4 which also stimulates the production of IgE antibody and IL-5?

• (Also induces Type I hypersensitivity reactions)

Ankylosing spondylitis (Bamboo spine disease)

Which disease is most commonly associated with HLA-B27?

• SLE

• DM I

• Grave’s disease

• Addison’s disease

• Myasthenia gravis

Diseases associated with HLA-DR3

• Myasthenia gravis

• Addison’s disease

• Celiac disease

Diseases associated with HLA-DR4

Chromosome 6

The genetic coding for the Major Histocompatibility Complex (MHC) is located in:

Class I MHC

Which MHC class presents antigen to CD8+ cells, destruction of virally infected cells, tumor cells, and graft rejection?

Class II MHC

Which MHC class presents antigen to CD4+ cells?

Molecular

It is the fastest and most superior method for identifying major histocompatibility complex (MHC) alleles

Restriction Fragment Length Polymorphism

The molecular method for identifying MHC alleles is also known as:

Mixed Lymphocyte Reaction

Which test for MHC is best for bone marrow grafts and living related donors?

B lymphocytes

HLA-DR typing requires identification of:

Nylon wool separation

B-cell suspensions can be prepared by:

Schlepper molecule (carrier)

It couples with haptenic groups which will confer new antigenic specificities

Preformed cytotoxic antibodies to donor antigens

What is the cause of a hyperacute graft rejection?

Previous sensitization to donor antigens

What is the cause of an accelerated graft rejection?

3 months

A patient who has received a solid organ transplant begins to show signs of chronic graft rejection. Which of the following best describes the typical timeline for the onset and progression of chronic graft rejection?

Acute graft rejection

A patient presents with signs of organ dysfunction approximately 10 days after receiving a kidney transplant. Biopsy reveals infiltration of lymphocytes and evidence of microvascular injury. Which of the following best describes the type of rejection occurring?

Accelerated graft rejection

A transplant recipient develops severe graft dysfunction within 3 days following transplantation. Histological examination of the biopsy shows extensive lymphocytic infiltration and tissue necrosis. This rapid onset suggests which type of graft rejection?

Between the CH1 and CH2 domains of the heavy chain

The hinge region of an antibody plays a critical role in its flexibility and function. Where is the hinge region located in the structure of an antibody?

Hinge region

The flexibility of the antibody molecule, particularly in its ability to bind antigens and activate immune responses, is largely attributed to which structural feature?

Papain

Which enzyme cleaves the immunoglobulin into 3 fragments and cleaves above the hinge region?

Pepsin

Which enzyme cleaves below the hinge region?

Agglutination and cytolytic reactions

IgM is a key antibody produced during the early stages of an immune response. Which of the following is a primary characteristic of IgM?

It is the major immunoglobulin in normal serum and has the longest half-life of any immunoglobulin class.

Which of the following statements is true regarding IgG in the immune system?

IgG1

Which subclass of IgG is most capable of crossing the placenta to provide passive immunity to the newborn?

IgG3

Which subclass of IgG is the most efficient at fixing complement?

IgG

Which immunoglobulin responds best to carbohydrate antigens?

IgA

It is the predominant immunoglobulin in secretions

IgD

• A cell membrane immunoglobulin found on the surface of B lymphocytes in association with IgM

• It serves a function in immunoregulation

Binds to mast cells and basophils, triggering the release of histamines and heparin upon antigen binding

IgE plays a central role in some types of hypersensitivity reactions. Which of the following is the primary function of IgE in allergic responses?

Parasitic infections

IgE is particularly important in immunity against which of the following?

Radioimmunosorbent Test (RIST)

Which test measures total serum IgE levels?

Radio Allergo Sorbent Test (RAST)

Which test measures allergen specific IgE?

It cleaves C3b and C4b to prevent further activation of the complement cascade.

What is the primary function of Factor I?

It serves as a cofactor for Factor I to inactivate C3b, and prevents Factor B from binding to C3b.

Which of the following is the primary role of Factor H?

It prevents the attachment of the C5b67 complex to cell membranes, thereby blocking MAC formation.

S protein, also known as vitronectin, plays an important role in preventing damage during complement activation. What is its primary function?

Decay Accelerating Factor

Which factor prevents the assembly of C3 convertase?

C1

It acts as the recognition unit of the classical pathway

• IgA aggregates

• Yeast cell/zymosan

• Cobra venom factor

• LPS

The alternate pathway is initiated by:

C3 convertase

In the lectin pathway, C4 and C2 are cleaved which forms:

C1 inhibitor

Deficiency of which complement leads to Hereditary Angioneurotic Edema (HANE)?

C1 (q,r, or s), C2, C4

Deficiency of which complement/s lead to Lupus-like syndrome?

C2

The most common complement deficiency is:

C3

The most severe complement deficiency is:

Radial Immunodiffusion (RID)

A method used to screen for individual complement components

Nephelometry

A method which measures concentration according to the amount of light scattered by a solution containing a antibody and a measured patient sample

Complement activity

Both RID and nephelometry give quantitative results but are unable to measure:

Hemolytic titration (CH50) assay

What is the most commonly used functional assay for the classical pathway? (measures lysis)

Liposome lysis

Which test is more accurate than the traditional CH50 assay?

Radial hemolysis

In this assay, rabbit RBCs that have been sensitized with an antibody are implanted in agarose, and patient serum is then added to wells punched in the gel.

Clear zone

In radial hemolysis, what is the appearance of lysis around each well?

ELISA

It is considered as the BEST SCREENING ASSAY for complement abnormalities

Sheep RBCs

What type of indicator is used in CH50 assay?

Rabbit RBCs

What type of indicator is used in AH50 assay?

• Magnesium chloride

• Ethylene glycol tetraacetic acid

When performing AH50, which substances are added to the buffer?