IMMUNOPATHOGENIC MECHANISMS OF HIV-INFECTION

A complex array of multiphasic and multifactorial immunopathogenic mec hanisms are involved in the establishment and progression of human imm unodeficiency virus (HIV) disease. After primary infection, acute vire mia occurs with wide dissemination of HIV. During this early viremic p hase, the virus is trapped within the processes of follicular dendriti c cells in the germinal centers of lymphoid tissue. Also, during this phase of primary infection, some patients show major expansions of cer tain subsets of CD8(+) T cells that are identified by the expression o f a particular variable region of the beta chain of the T-cell recepto r. These expansions are manifestations of responses to HIV that may be important in controlling the progression of HIV infection. in additio n, inappropriate immune activation and elevated secretion of certain p roinflammatory cytokines occur during HIV infection; these cytokines p lay a role in the regulation of HIV expression in the tissues. Infecti on of progenitor cells in bone marrow and the thymus contribute to the lack of regeneration of immuno-competent cells. Dendritic cells are i nvolved in the initiation and propagation of HIV infection in CD4(+) T cells. In studies of long-term nonprogressors-persons who have stable CD4(+) T-cell counts and no HIV disease progression despite years of HIV infection-preserved lymph node architecture, low viral burden, and viral expression were found.