Mouse erythrocyte formation. A marker for resting B lymphocytes.

The ability of peripheral blood lymphocytes to form rosettes with mouse erythrocytes was examined using lymphocytes from normal healthy individuals of various ages and of neoplastic lymphoid cells from patients with a variety of lymphoproliferative disorders. Our results indicated that only B lymphocytes form mouse rosettes (MR). The percentage of MR varied slightly according to the strain of mouse erythrocytes used in the assay. Little variation in the mean percentage of MR was observed when lymphocytes from various age groups of healthy individuals were studied. When neoplastic lymphoid cells were incubated with mouse erythrocytes only lymphocytes from patients with chronic lymphocytic leukemia formed an increased number of MR. Peripheral blood B lymphocytes lost their ability to form MR following incubation with pokeweed mitogen. These findings supported the view that the determinant on B lymphocytes which binds to mouse erythrocytes was present only at a resting stage of B cell maturation.