CD4 and viral infectious disease: In infected B6, Kb−/−xDb−/−, and Kb−/−xDb−/−xCD1d−/− mice, however, the percentages and absolute numbers of both CD4 and CD8 T cells were similar (Figure 2A and 2B), indicating that viral infection stimulated a massive expansion of CD8 T cells in mice lacking the Class Ia and CD1d molecules.