Fluctuation tests with antibody-forming spleen cell populations.

Shortly after immunization of mice, cells forming specific antibodies to one antigen, for example, sheep red blood cells, are nonrandomly distributed throughout the spleen. If the spleen donor has been immunized with two different antigens, for example, sheep red blood cells and chicken red blood cells, the nonrandom distribution of spleen cells forming antibody to one antigen differs significantly from that of cells forming antibody to the other antigen. These findings are in accord with a clonal distribution of antibody-forming cells.