Cellular immune responses in vitro were studied in 24 patients on chronic hemodialysis and 16 healthy volunteers with normal kidney function. Patients on maintenance hemodialysis had lymphopenia with diminished numbers of both T4+ and T8+ T-lymphocytes. The T4/T8 ratios were within the normal range. Peripheral blood lymphocytes (PBL) showed a diminished proliferative response upon stimulation with concanavalin A, phytohemagglutinin and pokeweed mitogen. When cell surface antigens were used for stimulation (mixed lymphocyte culture) uremic lymphocytes also showed a lower proliferation rate. Although without statistical conformation, there was a tendency by uremic PBL to produce less IL-2 as compared to healthy controls. Moreover, in a PWM driven system, peripheral blood lymphocytes from uremics produced significantly less IgG than PBL from normals. These results support the notion that a profound defect in lymphocyte function accounts at least, in part, for the observed immunodeficiency of uremic patients.

Cloned human cytotoxic T lymphocytes and monoclonal antibodies inhibiting their function (anti-T3A, anti-T4A, and anti-T8A) were used to elucidate the role of T cell surface glycoproteins in cell-mediated lympholysis involving individual classes of gene products of the major histocompatibility complex on target cells. The results indicate that several surface molecules are required for specific target recognition: T3 and T4 on T4+ cytotoxic T lymphocytes and T3 and T8 on T8+ cytotoxic T lymphocytes.

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The T cell receptor for antigen (Ti) has recently been identified as a 90-kdalton T3-associated clonotypic structure composed of one 49-51- kdalton alpha and one 43-kdalton beta subunit, which are disulfide linked. Here, Ti molecules from two alloreactive CTL clones derived from the same donor but of differing specificities (CT8III and CT4II) are directly compared following isolation with anticlonotypic monoclonal antibodies. Isoelectric focusing shows that the alpha subunits (pI 4.4-4.7) are more acidic than the beta subunits (pI 6.0- 6.2) but that each glycoprotein species is distinctive. More importantly, two-dimensional peptide maps of 125I-labeled surface receptors indicate that the beta chains of Ti1 and Ti2 appear unique and share only two peptides in common. In contrast, peptide maps of Ti1 and Ti2 alpha chains are more related although not identical. These results suggest that the human T cell receptor is composed of constant as well as variable regions and that at least one of the latter is located within the beta subunit.