Detection of three distinct patterns of T helper cell dysfunction in asymptomatic, human immunodeficiency virus-seropositive patients. Independence of CD4+ cell numbers and clinical staging

We have tested the T helper cell (T(H)) potential of asymptomatic, HIV seropositive (HIV⁺) patients, using an in vitro assay for IL-2 production. Peripheral blood leukocytes (PBL) from 74 HIV⁺ patients and 70 HIV^- control donors were tested for T(H) function when stimulated with influenza A virus (FLU), tetanus toxoid (TET), HLA alloantigens (ALLO), or PHA. Of the HIV⁺ patients, four different response patterns were observed: (a) patients who responded to all four stimuli (16%); (b) patients who were selectively unresponsive to FLU and TET, but responded to ALLO and PHA (54%); (c) patients who were unresponsive to FLU, TET, or ALLO, but responsive to PHA (16%); and (d) patients who failed to respond to any of these stimuli (14%). Our results indicate a time-dependent progression from a stage responsive to all four stimuli to a stage unresponsive to any of the stimuli tested, progressing in the order outlined above. The earliest T(H) defect is the loss of responses to FLU and TET, indicating a selective defect in CD4⁺ MHC self-restricted T(H) function. The later loss of ALLO and PHA IL-2 responses suggests more severe T(H) dysfunction involving both CD4⁺ and CD8⁺ T cells. None of these patterns of T(H) unresponsiveness in asymptomatic HIV⁺ individuals were correlated with CD4⁺ cell numbers nor with Walter Reed staging criteria. This study indicates that the in vitro T(H) assay used can detect multiple stages of immune dysregulation early in the course of HIV infection and raises the possibility that staging of HIV⁺ patients should include in vitro T(H) functional analyses of the type described here.