Isolation and localization of RNA fractions able to transfer tumor-specific delayed hypersensitivity in vitro

Abstract

RNA fractions were prepared by sucrose density gradient centrifugation from hot-cold phenol, RNA-rich extracts of lymphoid tissues from strain 2 guinea pigs hyperimmunized to line 1 or line 10 tumors. Each RNA fraction was assessed for its ability to convert nonsensitized strain 2 peritoneal exudate cells to a state of specific sensitivity for line 1- or line 10-solubilized tumor antigens. An RNA fraction residing between the 4 S and 18 S peaks, designated as Fraction "B", transferred line 10 or line 1 sensitivity in 12 experiments. Twelve additional RNA extracts containing 2 subfractions prepared from RNA fraction B, designated as B1 and B2, also transferred line 1 or line 10 sensitivity in 14 experiments. Except for 3 experiments where the 4 S or 18 S material transferred tumor-specific sensitivity, RNA fractions corresponding to approximately 4 S, 18 S, 22 S, and 28 S were unable to transfer tumor-specific sensitivity to nonsensitized peritoneal exudate cells. Treatment of fraction B with RNase results in complete loss of ability to transfer immunobiological activity.