Defective T-cell differentiation in acquired immune deficiency syndrome (AIDS).

A decline in T-cell lymphocyte number is the central characteristic of acquired immune deficiency syndrome (AIDS). The reason for the loss of these cells is not well understood. We investigated the hypothesis that defects in T-cell differentiation contributed to T-cell loss using an in vitro colony assay that measures T-cell precursor (CFU-T) frequency. The results indicate a substantial generalized decrease in CFU-T in people with AIDS (P less than 0.01), most of whom have Kaposi's sarcoma, and an occasionally severe decrease in CFU-T in people with ARC. Some of the cells from low colony formers suppressed colony formation by control cells. In addition, plasma from people with AIDS was less supportive of colony growth than control plasma. Decreased Ia expression on adherent mononuclear cells did not correlate with colony formation. A defect in T-cell repopulation can help explain the loss of T cells associated with AIDS.