Abstract
Antigen-binding cells of T and B origin can readily be determined by quantitating the number of sheep erythrocytes per rosette after glutaraldehyde fixation. The T(1) and T(2) populations have low antigen-binding properties and are very unstable without fixation. The B(1) and B(2) populations are stable and correlate with precursor and secretory cells. Fixation of rosettes permits a sensitive test for studying differentiation of T and B cells.