Transfer factor in vitro: Chromatography of components that enhance antigen-induced lymphocyte proliferation

Abstract

Human dialyzable transfer factor (TF-D) was obtained from two sources: commercial blood bank buffy-coat preparations and leukocyte-rich plasma of dextran-sedimented whole blood. After Sephadex G-25 chromatography of TF-D, column fraction pools were assayed for effect on antigen-induced lymphocyte proliferation in vitro. Both sources of TF-D gave broad elution patterns of proliferation-enhancing activity. However, a discrete activity pattern was obtained, with most of the active material appearing at one total column volume, upon fractionation of relatively small sample sizes of TF-D prepared by the dextran sedimentation method. Conditions of chromatography did not account for spread of activity since localized elution patterns were seen for radiolabeled markers such as polyamines, thymidine, cyclic AMP, cyclic GMP, folic acid, adenine, and hypoxanthine chromatographed in a mixture with TF-D. These observations, suggesting antigen-dependent enhancing activity from many of the chemically heterogeneous small (dialyzable) molecules in human TF-D, are supported by experiments showing such activity from physiological amounts of added folinic acid and by reports of others showing activity from nanogram amounts of added polyamines and vitamin A, although the quality and quantity of activity elution patterns suggest the presence of other active materials in addition to polyamines, vitamin A, and folates.