Non-histone chromatin proteins of mouse spleen cells during the primary immune response to sheep red blood cells and aggregated human gamma-globulin.

1. The protein/DNA ratio in chromatin of spleen cells increased during immunization; the ratio was the highest at the time of the maximum antibody synthesis, then decreased to the control values. 2. In the spleen cells of mice immunized with sheep red blood cells or aggregated human gamma-globulin, several characteristic fractions of non-histone chromatin proteins were preferentially synthesized: two antigen-specific fractions were observed in the phase of IgM and IgG synthesis, respectively, and the third, unspecific fraction was detected when the antibody synthesis ceased.