Tx: A component in human dialyzable transfer factor that induces cutaneous delayed hypersensitivity in guinea pigs

Abstract

This report describes the partial purification and characterization of the active component(s) in human dialyzable “transfer factor” (TFd) responsible for the transfer of cutaneous delayed hypersensitivity ( DM H ) to PPD into guinea pigs. TFd was fractionated on Sephadex G-25, and the active fraction obtained (TFg) was then subfractionated on Bio-Gel P-4. The active subfraction, termed Tx, contained at least six components on thin-layer chromatography; two of these appear to be unique to Tx. All the components in Tx were shown to be of molecular weight 1100–3500 by chromatography, dialysis, and ultrafiltration. Tx preparations contained protein and RNA but no DNA. In comparison with the original TFd preparation, the active subfraction Tx was purified approximately 2300-fold in terms of RNA and 900-fold in terms of protein. The fractionation scheme used resulted in no detectable loss of activity. Transfer factor activity in TFg was resistant to treatment with DNase I, RNase A, and chymotrypsin but was destroyed by treatment with nuclease-free Pronase or RNase T1. Preparations were also inactivated by heating for 30 min at 100°C but not at 56 or 37°C. The component(s) in human TFd responsible for passive transfer of D H into guinea pigs appear to share several physical and chemical characteristics with those responsible for the transfer of D H in humans.