FIG. 2.

NO₂⁻ production by macrophages is dependent on the concentration of B. bovis CM and IFN-γ. (A) Macrophages were stimulated with 6.25 to 200 μg of CM per ml alone (diamonds) or in the presence of 100 (circles), 500 (triangles), or 1,000 (squares) U of IFN-γ per ml. (B) Macrophages were incubated with B. bovis CM (100 μg per ml) and 0 to 1,000 U of IFN-γ per ml (diamonds), IFN-γ alone (circles), or CM plus IFN-γ in the presence of 250 μM l-NMMA (squares). (C) Macrophages were stimulated with B. bovis CM (100 μg per ml) in the presence of 0.03 to 8 U of IFN-γ per ml. The results are presented as the mean NO₂⁻ concentrations for quadruplicate cultures.