461. Which of the following statement regarding Type 3 Hypersensitivity reaction is FALSE?
A. Deposition of immune complexes is favored in slight antigen excess state.
B. The antigen involved are all endogenous antigen
C. Anaphylatoxin are activated, resulting in vasodilation & oedema
D. Tissue damage is due to formation of microthrombi & release of lysozyme from leukocytes
E. All of the above

462. Which of the following statement regarding tuberculin reaction is FALSE?
A. CD8+ T cells are the predominant cell type involved in tuberculin reaction.
B. Sensitized T cells release IFNy to activate macrophage at the site of reaction.
C. T cell predominates the reaction initially, then replaced by macrophages over 2-3weeks.
D. Reaction begins within 8-12 hours, peaking at 72 hours.
E. All of the above

463. Which of the following statement regarding immunologic tolerance is TRUE?
A. All B cells that bear receptors with self-antigen are deleted in the bone marrow & not released into the circulation.
B. Anergic T Helper cells can react to self-antigen if it is presented with MHCrr molecule & the 2nd signal in subsequent exposures.
C. TSllppressor cells recognize self-antigen & respond by down-regulation of immune responses
D. All of the above
E. None of the above

464. Autoimmune disease may occur due to:
A. Complexing of self antigen with drugs, leading to B cell stimulation
B. Cross reaction between microbe & self-antigen, leading to B cell stimulation
C. Non-antigenic stimulation of B cells by EBV.
D. Formation of self-antigen that is sequestered during development.
E. All of the above.

465. Which of the following regarding HIV is FALSE?
A. Heterosexual contact is the predominant mode of transmission of HIV worldwide.
B. All forms of transmission ofHIV are aided by coexisting STDs.
C. Transfusion of seronegative blood still has a small risk ofHIV transmission.
D. Seroconversion rate for HIV in needle-stick injury is 3%.
E. Perinatal transmission to neonate is the most common cause ofHIV infection in children.

466. Which of the following regarding HIV is FALSE?
A. HIV is a dsDNA virus.
B. HIV2 & HIVI have serologic cross-reactivity.
C. Viral envelope glycoproteins, gp 120 & gp41 are critical for HIV infection of cells.
D. HIV has tropism for hematopoietic & CNS cells.
E. HIV is capable of causing immunosuppresion.

467. Which of the following statement regarding my is TRUE?
A. mY has selective tropism for T Helper cells.
B. CD4 molecules on T cells & macrophages act as specific receptors for gpl20 envelope protein on my.
C. In the dividing T cells, my cDNA enter nucleus to integrate into host genome.
D. When HIY infected T cells are activated by antigens or cytokines, extensive viral budding occurs, leading to cell death.
E. All of the above.

468. Which of the following statement regarding my is FALSE?
A. Only 0.01-0.1 % of circulating T cells are productively infected, especially early in the disease process.
B. Productive infection is continually activated in the latently infected cells as antigenic exposure occurs.
C. There is increase in CD4:CDS ratio in the peripheral blood in AIDs.
D. More T cells are infected in lymphoid tissue than in the peripheral blood.
E. There is selective loss of memory subset of T Helper cells early in the disease process, leading to clonal anergy even with common recall antigen.

469. Which of the following statement is TRUE regarding the mechanism ofTHelper cells in my infection?
A. Extensive viral budding in the productively infected T cells lead to cell death
B. Direct infection of thymic progenitor cells or accessory cells that secrete trophic cytokines for CD/ T cell result in reduction in T cell maturation & number.
C. Fusion of infected T cells with uninfected cells results in formation of giant cells that balloon & die within a few hours.
D. Soluble gpl20 molecules can be released to bind uninfected CD/ T cells, resulting in antigen dependent cytotoxicity (ADCC) of both infected & uninfected T cells in the presence of antigp 120 antibodies.
E. All of the above

470. Which of the following statements regarding my infection of macrophages is FALSE?
A. Majority of infected macrophage are tissue macrophages (esp brain & lung), not circulating monocytes.
B. my may enter macrophages via phagocytosis or endocytosis of antibodies coated my particles.
C. Infected macrophage formed a reservoir, factory & safe vehicle for HIY.
D. Extensive viral replication in macrophages lead to macrophage cell death.
E. Infected macrophages have inappropriate secretion of TNFa, leading to upregulation of my production.

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