Human Transfer Factor in Vitro: Identification of L‐Serine and Glycine as Components with Augmenting Effect in Lymphocyte Transformation Assay

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Abstract
The components of human leucocyte dialysate thought to contain transfer factor, which irresponsible for its capacity to augment antigen or mitogen induced lymphocyte blasogenesis in vitro, were determined by comparing the activity of the original dialysate with its fractions derived from chromatography on Sephadex G‐10. Augmentation of leucoagglutinin (LA) induced transformation was only observed using the original dialysate and two fractions (IIb and IIc) eluting before the total volume of the column. These fractions contained the majority of free amino acids in the dialysate, and no trichloroacetic acid (TCA) precipitable material. Synthetic mixtures, containing the same amount of free amino acids as the fractions, augmented both tuberculin PPD and LA induced blastogenesis in a similar manner to the fractions. The augmenting activity of the synthetic mixture and hence, presumably, the dialysate fractions seemed to be due mostly to l‐serine and glycine, non‐essential amino acids not present in MEM‐S, the culture medium used. No augmenting affect by leucocyte dialysate was seen when MEM‐S was replaced by RPMI 1640, a culture medium containing both l‐serine and glycine. The results suggest that the non‐specific in vitro activity of leucocyte dialysate in this test may be due to a medium supplementation effect and that this phenomenon is probably not relevant to the nonspecific consequences of injection of transfer factor in vivo.