Concentration of murine antigen-specific transfer factor of defined potency.

Dialysates containing transfer factor (TF) activity were prepared from lyzed splenic cells of SPF mice immunized with live, peripherally avirulent Langat virus (TP21 E5 "14" clone) from the tick-borne encephalitis (TBE) complex. The amount of TF was estimated by its capacity to generate in recipient inbred C3H mice cytotoxic T lymphocytes inducing lysis of TBE virus-infected target cells as demonstrated by 51Cr--release assay. A 100 to 1000-fold concentration of TF activity was achieved by combination of the two-step ethanol precipitation of crude dialysates with subsequent fractionation on Sephadex G-25 by exclusion chromatography. Materials from individual concentration steps showed reduced amounts of admixtures, as revealed by absorbance profiles of their chromatograms. In the final product the protein content was most decreased.