Generation of mixed BM chimeras to assess the in vivo role of IL-4–producing B cells during cutaneous leishmaniasis. Recipient B cell-deficient mice (μMT) were lethally irradiated with a total of 1,000 rad (500 rad, two doses, 3 h apart). Twenty-four hours later, irradiated mice were reconstituted with 1 × 107 total BM cells per recipient mouse to generate the following chimeras: 50% µMT BM and 50% B-WT, 50% µMT BM, and 50% IL-4−/− BM (B-IL-4−/−). As controls, μMT recipient mice were reconstituted with 100% µMT BM (µMT), 100% IL-4−/− BM (IL-4−/−), while C57BL/6 recipient mice were reconstituted with 100% C57BL/6 BM (BL/6). Chimeric mice were allowed to reconstitute for 8 wk before repopulation was analyzed.