FIG. 2.

NK cells contribute to skewing toward the protective Th1 type. (a) Reduced Th1 cytokine production in anti-HSV CD4 and CD8 T cells. C57BL/6 mice were divided into two groups. One group was depleted of NK cells; the other group was administered control IgG and was infected with HSV by the footpad route. At 10 days p.i., their splenocytes were harvested and stimulated with UV-inactivated HSV or SSIEFARL peptide and analyzed for the CD4 and CD8 T-cell activity. Samples were processed individually, and similar patterns were observed within the same group. IFN-γ-producing CD4⁺ T cells and IFN-γ- and IL-2-producing CD8⁺ T cells in the control IgG, NK-depleted, and uninfected control animals are shown. The experiment was repeated three times with similar outcomes. The dot plot shows results obtained from one such experiment, and the numbers within the plot are the means ± SDs for five mice. (b) In vivo cytolytic ability is reduced in NK-depleted mice. Splenocytes from wild-type B6 mice were stained with CFSE and loaded with SSIEFARL peptide. A total of 5 × 10⁶ cells were adoptively transferred through the tail vein into control mice and NK-depleted mice. The spleens were isolated from these mice after 5 h and the splenocytes isolated. Target cells were distinguished from recipient cells based on CFSE staining. Histogram plots were used to demonstrate the difference in separation pattern based on intensity of CFSE staining. The recovery and percent killing of the various CFSE-labeled, peptide-pulsed targets were calculated as follows: 100 − ([(percentage of peptide pulsed in immunized mice/percentage of peptide unpulsed in immunized mice)/(percentage of peptide pulsed in unimmunized mice/percentage of peptide unpulsed in unimmunized mice)] × 100). The experiment was repeated two times with three mice in each group. The histogram plot shows the data obtained from one such experiment, and the number within the plot is the mean ± SD of killing ability for three individual mice.