Isolation and antigenic profile of follicular dendritic cells.

Follicular dendritic cells (FDC) were isolated from human tonsils and adenoids. With a simple modification of an isolation method described previously, FDC could be enriched up to 50%. The isolated FDC were characterized immunocytochemically. In contrast to previous studies, CD4 antigen was not detected on freed FDC, thereby suggesting that the CD4 molecule does not play a role in the infection process of FDC in AIDS, as has been demonstrated for T helper cells. Fc receptors could not be found on FDC by the panel of monoclonal antibodies applied, whereas C3 receptors were observed in abundance. Therefore, antigen trapping in germinal centres most probably involves only C3 receptors. This concept is in contrast with the current one (also developed on isolated cells), which postulates the involvement of Fc receptors. The extent to which C3 receptors are involved in the pathogenesis of AIDS will be examined in further studies.