T helper/inducer (CD4+) cells prestimulated with PPD induce monocytes to produce interleukin-1 beta.
We obtained peripheral blood mononuclear cells (PBMC) from four healthy, tuberculin purified protein derivative (PPD) reactive donors and cultured these cells in media containing PPD (low dose = 200 ng/ml or high dose = 1 micrograms/ml). Five days after the addition of PPD, T cells were isolated, washed, and added to autologous adherent cell cultures at a 1:1 ratio. Adherent cells were then cultured for 24 h in media only (baseline), media plus lipopolysaccharide (LPS, 2 micrograms/ml; positive control), or media containing the prestimulated T cells. After 24 h, supernatants were harvested and interleukin 1 beta (IL-beta) levels were assayed by radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA). The results show that T cells prestimulated with low dose PPD (200 micrograms/ml) did not induce IL-1 production by adherent cells (mean increase over baseline 0.2 +/- 1.3 standard deviation [SD] ng/ml, P = 0.61). However, T cells prestimulated with high dose PPD (1 microgram/ml) did induce adherent cells to secrete IL-1 beta (mean increase over baseline 1.7 +/- 0.62 [SD] ng/ml, P = 0.01), but this induction was abolished when cell-to-cell contact was prevented by use of double well chambers (mean increase over baseline 0.1 +/- 0.36 [SD] ng/ml, P = 0.69). Prestimulated T helper (CD4+) cells were able to induce monocytes to secrete IL-1 beta but prestimulated CD8+ T cells were not. These data suggest that when T helper (CD4+) cells are sufficiently activated they acquire the ability to induce monocytes to secrete IL-1 beta. Cell-to-cell contact between monocytes and T cells is required. This function of activated T cells may be important in the normal cellular immune response.
Dunlap
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Department of Medicine, University of Alabama, Birmingham 35294.
Tilden
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D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D002450:Cell Communication / Q000502:physiology; D002469:Cell Separation; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000502:physiology; D009000:Monocytes / Q000378:metabolism* / Q000502:physiology; D011863:Radioimmunoassay; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology*; D050378:T-Lymphocytes, Regulatory / Q000502:physiology; D014373:Tuberculin / Q000494:pharmacology*
D007375:Interleukin-1; D014373:Tuberculin