Figure 3.

Proliferation of Mtb-PPD-specific T lymphocytes following reactivation. Human lymphocytes were cultured with autologous DC and Mtb-PPD (autologous MLC) for 6 days. Following separation from MLC sensitized T lymphocytes were reactivated by different concentrations of Mtb-PPD in the absence of DC. The proliferative response of reactivated lymphocytes were determined by applying [³H]-thymidine assay (a). As control Mtb-PPD-specific T lymphocytes were reactivated by DC pulsed with the same concentrations of Mtb-PPD (b). The results of a representative experiment with lymphocytes from a donor are expressed as c.p.m. ± SD of three replicates. Evidence shows that in the absence of DC the more the Mtb-PPD concentration the less the proliferative rate of reactivated lymphocytes. Conversely in the presence of DC Mtb-PPD does not affect the proliferation activity of lymphocytes.