FIG. 2.

Flow cytometry of CD4⁺ T cells. CD4⁺ T cells producing IL-4 predominated in the IFN-γR^−/− mice, while those producing IFN-γ predominated in the 129/SvEv mice at all time points tested. Mice were sacrificed 10 days postinfection and LN cells restimulated in vitro with B. burgdorferi antigen-pulsed irradiated syngeneic spleen cells. At the indicated times cells were stained for CD4, IL-4, and IFN-γ and analyzed by flow cytometry. (A) Log₁₀ fluorescence of blast cells on day 8 is presented for a representative experiment of three; (B) Percent blast cells with the Th2 (CD4⁺ IL-4⁺) or Th1 (CD4⁺ IFN-γ⁺) phenotype for 129/SvEv and IFN-γR^−/− mice, calculated from results of flow cytometry, as a function of time in vitro.