CD4 and infection: Using general linear models to predict the relationship between peak viral load and virus-specific CD4+ and CD8+ T cells, we found that while 17 additional virus-specific CD4+ T cells/ml of BALF present at the beginning of infection would lower the peak viral load ten-fold, 450 additional virus-specific CD8+ T cells/ml of BALF would be needed at the beginning of infection to have the same effect.