CD4 T cell–derived IFNγ, but not IL-4 or IL-17A, plays a major role in immune reconstitution disease of M avium–infected TCRα^−/− mice. Totals of 2 × 10⁶ WT, IL-4^−/−, IL-17A^−/−, or IFNγ^−/− CD4 T cells were transferred into M avium–infected TCRα^−/− mice (n = 5 mice/group), as described in Figure 1, and (A) weight loss and (B) survival were monitored. The data shown in (A) are representative of 2-3 independent experiments, while the survival curves shown in (B) represent 9 mice pooled from 2 independent experiments. (C) TCRβ⁺CD4⁺ cells were measured in the PBMCs of the mice shown in panels A and B on day 9 after transfer. (D) IFNγ was measured by ELISA in the serum of the same animals on day 10 after transfer. (E) Levels of nitrate were measured in the same sera using a nitrate reductase assay, and TNFα levels (F) were determined by ELISA. (G) M avium–infected TCRα^−/− mice were reconstituted with WT CD4 T cells and then treated with anti-TNFα–neutralizing Ab or isotype control Ab on days 0, 3, 6, 9, and 12 after transfer, and weight loss was monitored. The data shown for each panel are representative of at least 2 independent experiments. In panels A and G, the shaded area between the traveling error bars represents the SD.