Interleukin 2 production in HTLV-III/LAV infection: evidence of defective antigen-induced, but normal mitogen-induced IL-2 production.

We studied mitogen- and antigen-induced interleukin 2 (IL-2) production in HTLV-III/LAV infected and non-infected individuals and compared the results with T cell subpopulations, and with mitogen- and antigen-induced DNA synthesis and production of leucocyte migration inhibitory factor (LIF) in order to understand the controversial findings related to IL-2 production in HTLV-III/LAV infection. The HTLV-III/LAV antibody positive group showed immunological defects: low T helper (Th) cells, high T-suppressor (Ts) cells, reduced mitogen- and antigen-induced DNA-synthesis, but LIF production comparable to the HTLV-III/LAV antibody negative group. The total amount of IL-2, produced either as a response to a mitogenic stimulus or as a response to a soluble antigenic (purified protein derivative of tuberculin, PPD) stimulus, was lower in the HTLV-III/LAV antibody positive group. However, adjusting the IL-2 production to the amount of Th-cells showed that the IL-2 produced by a standard number of Th-cells after mitogen induction was similar in HTLV-III/LAV infected and non-infected individuals. In contrast, the ability of Th-cells of infected persons to produce IL-2, or to proliferate as a response to a soluble antigenic stimulus, was considerably diminished. We conclude that HTLV-III infection leads to a selective incapability to mount a specific Th-cell response either due to an intrinsic defect in the Th-cell population or due to metabolic and/or functional disturbances in antigen-processing and presenting accessory cells.