Figure 4

FV-specific CD4⁺and CD8⁺T cell responses in the absence of NK cells. CB6F1 mice were infected with FV and one group of mice was NK cell depleted. Bone marrow and spleen cells were analyzed at 30 dpi. For the analysis of activated (CD43⁺ CD44⁺) virus-specific CD4⁺ T cells, bone marrow (A) and splenic (B) cells were stained with MHC class II-antibody tetramers specific for F-MuLV env fn20 [11]. Numbers of total CD8⁺ T cells were analyzed by flow cytometry in bone marrow (C) and spleen (D). Numbers (E, F) and percentages (G, H) of activated (CD43⁺ CD62L^-) effector CD8⁺ T cells, which are specific for the FV gagL epitope, were stained for D^bgagL class I tetramers and determined by flow cytometry in bone marrow (E, G) and spleen (F, H). Bone marrow (I) and splenic (J) activated CD8⁺ T cells were stained intracellularly for IFN-γ. A minimum of seven mice were used for analysis. At least two independent experiments were performed. Significant differences between the groups were analyzed by using the unpaired Students t test (** for p < 0.01) statistically significant by an unpaired t test (** for p < 0.01).