Figure 6.

Effect of Fas on re-call response of reactivated Mtb-PPD-specific T lymphocytes. Mtb-PPD-specific human T lymphocytes were reactivated by different concentrations of Mtb-PPD. The death receptor Fas was blocked on Mtb-PPD-specific lymphocytes by a neutralizing anti-Fas antibody (a and b, white bars). As control irrelevant mouse IgG was added to the cultures (a, b, black bars). The proliferative and apoptotic rates of reactivated lymphocytes were determined by applying [³H]thymidine assay (a) and TUNEL (b), respectively. The results of a representative experiment with lymphocytes from a donor are expressed as ±SD of three replicates. Evidence demonstrates that following Fas-blockade the proliferative rate of Mtb-PPD-specific lymphocytes reactivated by 100 or 400 µg/ml Mtb-PPD increases (a, white bars), when compared to the controls (a, black bars) (P < 0·05). Conversely Fas-blockade leads to a decrease in apoptotic rate of Mtb-PPD-specific reactivated by 100 or 400 µg/ml Mtb-PPD (b, white bars), when compared to the controls (b, black bars) (P < 0·05).