Dialysable specific transfer factor in mice immunized with attenuated Langat virus from the tick-borne encephalitis...

Cytolytic T lymphocyte assay was developed in order to measure the response of inbred C3H mice to dialysable specific transfer factor (STF), induced in subadult outbred mice by one shot immunization with the attenuated Langat virus. The first STF activity in mice splenic leukocytes was detected between 48-72 hr after virus administration. The conversion of splenic T-cell cytotoxic response in C3H mice in vivo occurred between 15-21 hr after STF administration. The killing activity of T-cells, induced by STF, showed cross-reactive traits within the genus Flavivirus. STF, given prior to the live virus, augmented the specific cytolytic T-cell response. In the live virus-primed mice the booster effect was markedly enhanced when administration of STF preceded the second immunization dose. In the serum of STF recipients, interferon was irregularly detected attaining low levels for short time periods. Temperature of 56 degrees C for 60 min abolished the activity of least 10(4) murine STF units, temperature of 37 degrees C lowered after 24 hr this activity by 3 log10units. Chromatography of the dialyzed leukocyte lysate on Sephadex G-25 column yielded usually five peaks. The second peak showed an increased content of ribose-bound and protein materials and, as a rule, a relatively concentrated STF activity.