Figure 3.

Adenosine deaminase (ADA) increases cytokine secretion in cultures of anti-CD3-triggered T cells from healthy donors. T cells from healthy donors were stimulated with 1 ng/ml anti-CD3 in the absence or presence of 4 μm ADA and cytokine levels were determined at days 2 and 6 (a) or day 2 (b) in culture supernatants as indicated in the Materials and methods. (a) Cytokine production when cells were stimulated with anti-CD3 in the absence (black columns) or presence of 4 μm ADA (white columns); data from one representative experiment of five are shown. Data are the mean ± standard deviation of triplicates. (b) Cytokine production in culture supernatants of anti-CD3-triggered T cells from five healthy donors in the absence of ADA (anti-CD3), in the presence of 4 μm ADA (anti-CD3 + ADA) or in the presence of 4 μm ADA but with preincubation of T cells for 15 min with 33 μg/ml of the monoclonal antibody anti-CD26 Ta5·9 (anti-CD3 + ADA + Ta5·9). Values are expressed as in-folds, calculated as the ratio of the cytokine concentration (pg/ml) produced by stimulated T cells versus that produced by non-stimulated T cells. Each symbol represents a healthy donor. Data are the mean ± standard deviation of triplicates. For each donor, IL-2 and IL-4 production was also analysed, and was < 12 pg/ml or even undetectable (data not shown).