CD4 and infection: Skewing of T cell subset proportions in CBA/J mice could be better appreciated by determination of CD4∶CD8 ratios throughout the course of infection (Fig. 1c), where a significant decline in the ratio of CD4+ to CD8+ T cells was observed by day 90 of Mtb infection, preceding the increasing CFU within the lungs of CBA/J mice (Fig. 1d) [4], [6].