Proliferation and interleukin-2 production in PBMCs exposed to the SHP-1 inhibitor PTP-1. (A) PBMCs were isolated from young (filled columns) and elderly (empty columns) donors, left untreated or exposed to the SHP-1 inhibitor PTP-1 (50 ng/ml) for the indicated times. The cells were non-stimulated (NS) or cultured in the presence of a mixture of anti-CD3 and anti-CD28 (5 μg/ml each) mAbs, or PHA (5 μg/ml) for 72 h. Cell proliferation was assayed by incorporation of [3H]thymidine. Data are represented as the mean ± SD. Letter (a) corresponds to statistical significance (one way ANOVA) for p < 0.05. Non-significance was observed for data relative to results obtained in PBMCs stimulated in the absence of PTP-1. Data are representative of one of 9 independent experiments using different donors. (B) Similar conditions of PBMCs treatment in the absence or presence of the inhibitor (I) PTP-1 with the mixture of anti-CD3/anti-CD28 (5 μg/ml each) mAbs or a combination of PMA (50 ng/ml) and ionomycin (iono) (1 ng/ml) were performed for the periods of time indicated. The extent of IL-2 production in non-stimulated (NS) or stimulated T cells was determined by FACS analysis of permeabilized cells using a FITC-labelled anti-Il-2 mAb. Results obtained in the case of young and elderly donors are shown using filled and empty columns, respectively. Letter (b) corresponds to statistical significance (one way ANOVA) for p < 0.05. Data are representative of one of 5 independent experiments.