Inhibitory effect of alpha-globulins of different origin on the cell-mediated immune responses in mice.

alpha-Globulins prepared from different biological sources (human and bovine sera, mouse ascitic fluid, human ovarian cyst fluid) were separated by ion exchange chromatography on DEAE-cellulose into fractions A, B and C. Whereas fractions A and B had no immunosuppressive activity, fraction C injected into mice shortly before antigen administration, but not after, significantly inhibited the contact sensitivity to oxazolone. Single high doses were preferential over divided doses given on several occasions. In transfer experiments when cells of animals sensitized to oxazolone were injected into recipients treated previously with fraction C, the response was also inhibited. Fraction C, when administered into F1 hybrid mice before injection of parental splenocytes, prevented the development of GVH reaction. The authors point out that the critical concentration of alpha-globulins at the time of antigen administration is necessary to make T-lymphocytes hyporesponsive, and when once triggered by antigen they become refractory to alpha-globulins action.