In situ quantitation of lymph node helper, suppressor, and cytotoxic T cell subsets in AIDS.

We have used the novel monoclonal antibodies 9.3 and anti-Leu-8 in conjunction with other T cell markers to quantify T cell subpopulations in the paracortex, mantle, and germinal center compartments of frozen sections of lymph nodes from seven homosexual men with acquired immunodeficiency syndrome (AIDS) and five heterosexual controls. Antibody 9.3 allows dissection of the Leu-2+ cytotoxic/suppressor subset (Tcs) into 9.3+ cytotoxic cells (Tc) and 9.3- suppressor cells (Ts). Anti-Leu-8 allows dissection of the Leu-3+ helper subset (TH) into functionally distinct subpopulations. The data indicate that the T cells in patients with AIDS exhibit normal antigen expression but altered subset ratios. In this series, the data suggested that the reversal of the paracortical TH-Tcs ratio was due to an increase in Ts with a concomitant decrease in TH and Tc. These changes were also reflected in a reversal of the normal paracortical Tc-Ts ratio (3.0) to less than 1.0. Furthermore, the data suggested a marked decrease in paracortical Leu-3+8+TH, which are known to have inducer function in cellular immune reactions and exert feedback inhibition of immunoglobulin production through a suppressor T cell intermediary. In contrast, there was preservation of the Leu-3+8-TH population within the germinal center. This T cell subset is known to help B cell differentiation. This microenvironmentally specific constellation of T cell subset alterations within lymph nodes may in part explain several of the immunologic findings associated with AIDS.