THE EXPRESSION OF B-CELL SURFACE-RECEPTORS .3. THE MURINE LOW-AFFINITY IGE FC RECEPTOR IS NOT EXPRESSED ON LY-1 OR LY-1-LIKE B-CELLS

The distribution of IgE FcR (Fc-epsilon-R)-positive and -negative B cells was examined in normal adult mice. Using three-color flow cytometry, the expression of the Fc-epsilon-R was analyzed on various B-cell subsets present in the peritoneum and spleen. The results demonstrate that in the peritoneal cavity, the Fc-epsilon-R is not expressed on the large majority of Ly 1+ B cells and Ly 1-, Mac 1+ sister B cells. The receptor is present, however, on the small number of conventional B cells residing in the peritoneum. Although interleukin 4 (IL-4) can increase the levels of the Fc-epsilon-R on conventional B cells, incubation of Ly 1 and sister B cells with IL-4 did not result in the expression of the Fc-epsilon-R. When examining B cells present in the spleen, a small subset of B cells was consistently found to be Fc-epsilon-R-. These Fc-epsilon-R- cells were IgM-bright, IgD-dull and largely Ly 1- and Mac 1-negative. Staining of splenic tissue sections revealed that the Fc-epsilon-R- B cells were primarily localized to the marginal zones, whereas the Fc-epsilon-R+ B cells were found in the follicles. Taken together, the results indicate that the Fc-epsilon-R may be a useful marker in delineating the various B-cell subsets. In the peritoneum, the Fc-epsilon-R appears to discriminate conventional B cells from those of the Ly 1/sister lineage, and in the spleen it is likely to distinguish resting follicular B cells from Ly 1/sister and marginal zone B cells.