Figure 1.

Lack of B-1 cell replenishment after PerC transfer into adult μ^−/− recipients. PerC from C57/Igh^a donors was transferred into adult μ^−/− mice, C57BL/6 neonates treated from birth for two month with anti-IgM^b, and into adult RAG-1^−/− mice. 5% contour plots of recipient PerC cells are shown, stained for total (Igh^a + Igh^b) and allotype-specific IgM and IgD of live, nonT cells/nonmacrophages (Fig. 3B). B-1 cells were identified as IgM^hi IgD^lo and B-2 cells as IgM^lo IgD^hi. Additional staining for CD5, CD11b, and CD23 confirmed their belonging to the different lineages (not shown). Data are summarized in Table 1.