GERMINAL CENTER CD4-CELLS ARE AN IMPORTANT SITE OF HIV REPLICATION IN-VIVO( T)

Objective: CD4+ T cells are the main target for HIV. However, the high est HIV antigen concentration in infected subjects accumulates on the cell surface of follicular dendritic cells in the germinal centres of the lymphoid tissue. Germinal centres contain a T-helper cell subset w hich expresses CD57 molecules. Here we analysed virus replication and viral load in CD57+CD4+ germinal centre T cells and in the CD4+ T cell s found mostly outside germinal centres (CD57-CD4+). Methods: Peripher al blood mononuclear cells and lymph-node cells were prepared, stained for CD4 and CD57 and purified by FAGS. Defined cell numbers of CD4+CD 57+ cells and CD4+CD57- cells were sorted directly into polymerase cha in reaction (PCR) tubes by FACS, equipped with an automated cell depos ition unit and analysed by PCR to detect proviral DNA. Based on Poisso n distribution, the expected level of infection was calculated. Viral replication was determined by amplifying double-spliced, single-splice d, and full-length transcripts of HIV using serially diluted cDNA of t he FACS-sorted cells. Results: An up to 10-fold higher frequency of in fected cells was found in the CD57+CD4+ germinal centre T cells compar ed with CD57-CD4+ T cells. Furthermore, active viral replication was d etected almost exclusively in the CD57+CD4+ T cells. Conclusions: The CD57+CD4+ germinal centre T cells are one of the sites of HIV infectio n and replication that may play a pivotal role in the pathogenesis of HIV infection.