Question

1.Would you expect the viral load in the blood of HIV-infected individuals in the early years of the asymptomatic phase of HIV-1 infection to vary significantly (assuming no drug treatment)? What about CD4+ T-cell counts? Why? Explain.

2. Beginning with sensitisation, describe the immune events that you expect to take place following the transplantation of a kidney between nonidentical siblings who share half their MHC molecules. You can assume that they are matched for ABO blood group antigens and have successfully passed the cross-match (i.e., they are antibody negative in a cross-match test). Explain.

3. What is the biologic basis for attempting to use soluble CTLA-4Ig or anti-CD40L to block allograft rejection? Explain

Answer 1

1.Eventhough the infection into a chronic stage starts only after the antibodies are formed in the body,during the initial period of infection following the entry of virus and thereby the viral antigens can be detected in the plasma within weeks.This is because the virus has already started to take over the cells machinery and hence there is integration of viral particles within the body resulting in the presence of viral antigens.

For CD4+ cells the levels tend to decline during this period because during the course of the T cells to fight the antigen the virus inturn kills these cells resulting in the reduction of their number

2.The first step is sensitization where the Cd4+ and CD8+ cells proliferate that recognizes the non self antigen followed by the effector phase where antibodies are developed against the antigen.When half the MHC molecules are same the chances of graft rejection are reduced by half because those antigens are not identified as non self

3.Soluble CTLA-4-Ig when used causes the selective inhibition where the Tcells are proliferated in allograft rejection.This inturn reduces the chances of rejection.