QUESTION 1 (16 POINTS): CHOOSE THE CORRECT ANSWER:

  1. Primary lymphoid organs are
  1. The sites where T and B cells expose to foreign antigens
  2. The sites where primary responses are initiated
  3. The sites where T and B cells mature
  4. None of the above
  1. Rapid but non-specific immune responses are mediated by
  1. Cells of the adaptive immune system
  2. Cells of the innate immune system
  3. Leukocytes
  4. Memory responses
  1. A fundamental difference between the BCR and TCR is
  1. The nature of antigens they recognize
  2. BCR is on macrophages while TCR is on neutrophils
  3. BRC recognize proteins but TCR don’t
  4. The location on cell membrane
  1. Which one group of the following cells is NOT phagocytic in nature?
  1. Neutrophils
  2. B lymphocytes
  3. Macrophages
  4. None of the above
  1. Antibody affinity for antigen depends on
  1. The antibody isotype
  2. The complementarity between the antibody Fab and epitope
  3. The number of Fab regions in the antibody molecule
  4. Whether the antibody is in the serum or on the cell surface
  1. Immunoglobulin G (IgG) is
  1. Important in mucosal immunity
  2. Produced by naïve B cells
  3. The principal Ig in the secondary immune responses
  4. The only Ig capable of activating B cells
  1. Peripheral lymphoid tissues
  1. include spleen, thymus and lymph nodes
  2. are the sites where naïve T and B cells encounter antigens
  3. are the sites where T and B cells learn to tolerate self antigens
  4. None of the above
  1. B cells are distinguished from T cells by the presence of
  1. CD3
  2. CD8
  3. CD4
  4. MHC class II
  1. The immunoglobulin isotype is determined by the
  1. Antigen specificity
  2. Heavy chain constant region
  3. Light chain variable region
  4. Number of antigen-binding sites
  1. Isotype switching
  1. Means that B cells produce all isotypes simultaneously
  2. Is regulated by helper macrophages
  3. Means production of antibody by memory cells
  4. Is a property of B cells to switch from IgM to IgG
  1. ADCC is a process in which antibody-coated cells are killed by
  1. the antibodies
  2. complement
  3. CD8 T cells
  4. NK cells
  1. Avidity
  1. Is a pathogenic agent, causing a very serious disease
  2. Occurs when the ratio of antibody to antigen is optimal
  3. Refers to the strength of interactions between an antibody and an antigen
  4. Results in a loss of antibody reactivity
  1. Natural Killer cells
  1. Kill normal cells with high levels of membrane MHC Class I
  2. Recognize virus-infected cells that displaylow levels of membrane MHC Class I
  3. Secrete the complement to lyse virus-infected cells
  4. None of the above
  1. IgE
  1. Is bound together by J chain
  2. Binds to mast cells
  3. Is found as a pentamer
  4. None of the above
  1. Which of the following Ig isotypes medicates the major antibody response against helminthparasites?
  1. IgA
  2. IgE
  3. IgM
  4. IgG
  1. Immunological tolerance means
  1. Reactivity to self antigens
  2. Unresponsiveness to self antigen
  3. Maturation of B and T cells in lymph nodes
  4. Development of B and T cells in Thymus

QUESTION 2 (4 POINTS): Pathogens occupy different cellular locations: extracellular and intracellular. What is the main immune response to antigens at different locations?

QUESTION 3 (15 POINTS): ANSWER ONLYTHREE OF THE FOLLOWING QUESTIONS (5 POINTS FOR EACH QUESTION)

A) Discuss the functions of different antibody isotypes in the humoral immune responses!

B) How T cells recognize antigens?

C) What is the role of antibodies and complement in phagocytosis?

D) Discuss the importance of CD4 T-cell help to B-cell responses against protein antigens!!

E) Draw and label the structure of the antibody!!