FIG. 4.

Production of active TGF-β by C. albicans infected human peripheral blood monocytes. Peripheral blood monocytes were collected as described in Materials and Methods and cultured in defined medium with blastoconidia for the indicated time intervals. (A) The medium was collected and assayed for the presence of TGF-β, and the result was compared to a standard curve generated by the response to recombinant human TGF-β1 (B and C) The conditioned medium samples collected at 12 h (B) and 24 h (C) each contained an activity capable of inhibiting the proliferation of Mv1lu cells (black bars) in a manner reversible by a TGF-β neutralizing antibody (white bar) but not by a nonneutralizing, isotype control IgG (hatched bar), thereby demonstrating TGF-β- specificity of the neutralization of growth inhibition. Levels of TGF-β were most notable at target-to-effector-cell (T:E) (yeast/monocyte) ratios of 10:1 and 1:1. The results in panels B and C are the mean of three separate experiments for conditioned medium at a 1:2 dilution.