The stimulatory activity of IF in the rat thymocyte proliferation assay was inhibited by an excess of human recombinant IL-lra (10 |xg/ml) (Fig. 2). This concentration of IL-lra completely inhibited the hrIL-1 (3 standard over the same dose-response range (data not shown). However, in four experiments out of a total of nine experiments, two IF pools retained a minor proportion (30-49%) of their stimulatory activity even in the presence of the IL- Ira, indicating the presence of minor amounts of lymphocyte growth-stimulating activities that could not be attributed to IL-1.
These data indicated that while bioactive IL-1 is present in testicular IF from normal adult rats, the principal action of the IF on T cells is inhibition of activation/proliferation. buy flovent inhaler
Specificity of the IF Inhibitory Activity
Cell viability was assessed using propidium iodide vital staining and flow cytometric analysis. The viability of unstimulated rat thymocytes after 72 h in culture was 36% and 32% in two experiments, 25% and 27% for PHA-stim-ulated thymocytes, and 33% and 66% in the presence of IF (10 jjlI), indicating that the inhibitory effect of IF was not due to nonspecific cytotoxicity.
FIG. 2. Comparison of the effect of testicular IF on PHA-induced [3H]thymidine incorporation in the rat thymocyte proliferation assay, in the absence (open bars, open circles) or presence (solid bars, solid circles) of a maximally inhibiting dose of human recombinant IL-1 ra (10 |xg/ml). Values are mean ± SEM, n = 4 replicate wells. Values with same letter superscript are not significantly different (p < 0.05).