Host B cells attenuate the production of inflammatory cytokines after allogeneic BMT. μMT allogeneic recipients (□, n = 8), wild-type allogeneic recipients (▪, n = 8), and μMT syngeneic recipients (▦, n = 4) mice received transplants as in Figure 3. (A) IFNγ levels were measured in sera on days 5, 7, and 10 after BMT, and (B) TNFα at day 10 as described in “FACS and cytokine analysis.” Results represent mean ± SE of individual animals. (C) Peritoneal macrophages were harvested from animals on day 10 after BMT and stimulated with LPS (1 μg/mL) as described in “Cell cultures.” TNFα was determined in culture supernatant by ELISA. Results are normalized to production per 10⁵ macrophages based on CD11b staining. *P < .05 versus wild-type allogeneic recipients. (D) Donor H-2d+CD4⁺ and CD8⁺ cells were sorted 2 weeks after BMT from allogeneic μMT (□) or wild-type (▪) recipients. CD4⁺ cells were stimulated in MLC with allogenic H-2^b+ CD11c⁺ DCs. Levels of IFNγ, TNFα, and IL-5 were determined in cell-culture supernatants as described in “FACS and cytokine analysis.” Cytotoxic T lymphocyte (CTL) activity of donor CD8⁺ T cells was tested in a standard ⁵¹Cr release assay as described in “Cell cultures.” Results are expressed as mean ± SE of triplicate wells. ND indicates not detected.