subject: IMMUNOLOGY OF AIDS [print this page] IMMUNOLOGY OF AIDS IMMUNOLOGY OF AIDS
In vitro, HIV produces a cytopathic effect in susceptiblecell lines, multinucleate giant cells (syncytia) form and celldeath occurs. The mechanism(s) by which it producesimmune dysfunction in vivo are not yet fully understood,but may include a direct cytopathic effect of HIV on theCD4 lymphocyte, HIV-specific cellular immune responsesdirected towards infected cells, and the triggering of programmedcell death (apoptosis) by viral proteins.Different factors, both viral and host determined, arelikely to influence the rate of disease progression. A smallnumber of HIV-infected persons, however, show little evidenceof immunosuppression many years after acute infection(long-term non-progressors). It is thought that thebreadth of the immune response to the different HIV antigens at the time of primary infection is pivotal in determiningdisease progression. In most infected persons thereis a rapid loss of specific T-helper cell and CTL responsesto multiple HIV antigens during primary infection, whichdo not recover during chronic established infection. Inpersons where these specific immune responses are preserved,plasma HIV RNA levels are low, viral replicationis contained and clinical disease progression slow. A betterunderstanding of these specific protective immuneresponses may lead to a more complete knowledge of theimmunopathogenesis of AIDS and the possible developmentof a protective vaccine.
