Effects of human transfer factor on the migration of guinea-pig macrophages: is there an antigen-specific activity?

Dialysable transfer factor (TF) prepared from the buffy-coat cells of tuberculin-positive human donors exerted antigen (PPD)-dependent inhibition of migration of guinea-pig peritoneal exudate cells (PEC) provided that migration of the cells was not strongly affected by PPD alone. TF from tuberculin-negative donors did not do this. The effect could be better demonstrated with tuberculin-sensitive than with normal PEC. Differences in the actions of 'tuberculin-positive' and 'negative' TF may also be seen in the absence of antigen. In a similar but more restricted series of experiments with diphtheria toxoid (DT) as antigen, DT-dependent inhibition was observed only with 'DT-positive' TF. The findings concerning antigen-dependent inhibition in both the tuberculin and toxoid systems are compatible with the concept of an antigen-specific TF, but it is argued that they should not be taken as strong evidence of such specificity. In the tuberculin system the results suggest an alternative explanation, namely that 'tuberculin-positive' TF contains a higher level of a non-specific activity. Whether specific or not, the antigen-dependent activity probably involves a stimulatory action on antigen-induced lymphocyte activation leading to enhanced production of macrophages migration inhibition factor, and it could be related to the 'transfer' phenomenon in vivo.