The decreased percentage of cells expressing IL-2 and IFN-gamma in conjunction with an increased proportion of IL-4- and IL-10-producing cells among the CD4+ T cells in HIV-1-infected individuals demonstrate a Th1 to Th2 cytokine shift in the course of HIV infection on a single cell level. There was no evidence of a Th1 to Th0 cytokine shift. In addition to the loss of CD4+ T cells in HIV infection, the qualitative changes of Th1/Th2 cytokine expression may serve as a marker for progressive failure of cell-mediated immunity.

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Summary. Dysregulation of T-cell receptor (TCR) ab bearing lymphocytes and an increase in Vd1þ gd T cells are typical features of HIV-1 infection. However, the role of gd T cells remains unclear. Therefore, peripheral blood mononuclear cells (PBMC) of 103 HIV-1-infected patients were investigated with respect to expression of Vd1. These results were compared to the Vd1 expression of bone marrow mononuclear cells (BMMC). In contrast to healthy controls, Vd1

Immunological investigations were carried out in an HIV‐1/2//HTLV‐1‐negative patient with CD4 T‐cell deficiency (0.357–0.6 × 109/l) and expansion of γδ T cells which accounted for 26–42% of peripheral blood lymphocytes during an observation period of 3 years. Flow cytometry analyses with a panel of available Vγ/Vδ‐specific monoclonal antibodies indicated that the pathologically expanded γδ population expressed Vγ2 or Vγ3 paired with Vδ3 on the surface but lacked the expression of activation antigens such as CD38 or CD71. Cloning and sequencing of RT‐PCR products obtained after amplification of cDNA with Vγ‐Cγ and Vδ‐Cδ specific primers confirmed the presence of a clonally expanded Vγ3/Vδ3 population in the peripheral blood of this patient. Cytotoxicity assays performed with purified γδ T cells as effectors and resting or preactivated autologous CD4 T cells as targets failed to reveal evidence for autoreactive cytotoxicity of Vγ3/Vδ3 cells as a possible mechanism of CD4 T‐cell deficiency in this patient.

The influence of hypericum extract LI 160 on the expression of serotonin receptors was investigated using a neuroblastoma cell line to establish a model for the regulation of neurotransmitters by immunologically active compounds such as cytokines. The cells were incubated with hypericum extract LI 160 in kinetic form for 2, 4, 6, 8, and 10 hours, then washed. The serotonin receptor expression analysis was compared to that of a placebo control solution. The neuroblastoma cells showed a clearly reduced expression of the serotonin receptors under treatment with hypericum extract. First stimulation experiments with interleukin-1 (IL-1) and hypericum extract suggest that a further reduction of the serotonin receptors is possible when IL-1 is added.