Figure 2

Body weight, immune parameters, and survival in aging M. tuberculosis infected HET3 mice. Peak body weights of M. tuberculosis infected aging mice (N = 40) (A) and the rate of weight loss (B) as compared to survival. There was no significant correlation between peak body weight and survival (Spearman r −0.1082, p = 0.26) (A). A strong negative correlation was identified between the rate of weight loss and survival (Spearman r −0.7123, p < 0.0001) with dashed lines showing the 95% confidence intervals (B). Blood was sampled to quantify naïve CD4 T cells prior to infection and then after infection at monthly intervals to quantify the average ESAT-6-specific IFN-γ responses for each mouse. No significant correlation was identified between naïve CD4 T cells and survival (Spearman r −0.2775, p < 0.08) (C), but there was a weak positive, statistically significant correlation between ESAT-6 specific IFN-γ and survival (Spearman r 0.3694, p < 0.02) (D). Data were censored for 11 old mice due to non-TB morbidity.