The TCR/CD3 receptor complex plays a key role in antigen recognition and T-cell activation. Therefore, the present study investigates TCR α/β (TCR1) and CD3 receptor density (RD, number of receptors per cell) on uremic helper-inducer (CD4) T lymphocytes in relation to T-cell proliferative response induced by anti-CD3 monoclonal antibodies (mAb). We found, that: (1) the number of TCR/CD3 receptors on uremic helper-inducer (CD4) T lymphocytes is decreased and correlated well with the blunted lymphocyte proliferation induced by anti-CD3 mAb; (2) these findings were associated with diminished binding capacity of IL-1β and IL-6 to their receptors (IL-1R, IL-6R) on helper-inducer T cells, whereas (3) the IL-2 receptor (IL-2R) and molecule expression of CD4 and lymphocyte function antigen-1 (LFA-1) were increased, and (4) uremic monocytes displayed a decreased density of intercellular adhesion molecule-1 (ICAM-1) expression, which interacts as receptor-ligand pair with LFA-1. The incubation of uremic and control peripheral blood mononuclear cells with uremic serum enhanced these above-mentioned changes in the expression of examined receptors and molecules. These data might also support the hypothesis that the blunted T-cell response to antigen in uremia is due to downregulation of the TCR/CD3 receptor complex by uremic milieu.

Cellular aspects of the immunomodulating activity of the galactoside-specific lectin from mistletoe (ML-1) were investigated in 10 cancer patients. Regular subcutaneous injections (4 weeks) of the optimal dosis of ML-1 (1 ng per kg body weight, twice a week) yielded notable increases in the apparent numbers of certain lymphocyte subsets [pan T cells; helper T cells; natural killer (NK) cells] which are generally believed to be involved in antitumor immunity. Moreover, ML-1 administration resulted in an increased level of expression of interleukin (IL)2 receptors on lymphatic cells, an indicator of cellular activation. In vitro, the exposure of human lymphocytes to ML-1 resulted in an enhanced expression of receptors for IL-2 (T cells) and HLA-DQ (B cells), which similarly substantiated the capacity of ML-1 to affect immunological parameters within the host defense system. Thorough clinical trials are now required to assess any impact of the application of the lectin on the course of the disease.

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