FIG. 8.

Endogenous CD46 ligands have differential effects on T cell activation and expansion phases of BCG-induced T cell responses. Soluble CD46 molecules were produced by refolding of bacterial inclusion body material and then purified to remove endotoxin. This recombinant protein was found to bind CD46 MAb. As described above, CFSE-labeled human PBMC were infected with BCG in fresh medium. Soluble CD46 (10 μg/ml) was added either at day 0 or day 3 of the 7-day culture period to saturate the culture with binding sites for potential ligands to CD46 (and thus block signaling). CD4⁺, CD8⁺, and γδ T cells responding to BCG (CFSE^lo IFN-γ⁺) were detected by flow cytometry. The data are normalized to the absolute number of responding T cells in each subset detected in parallel cultures infected with BCG. Asterisks indicate statistically significant differences between day 0 and day 3 groups (n = 8; P < 0.05 by Wilcoxon matched pairs test).