CAMP and infection: Moreover, comparing LL-37 mRNA expression in peripheral blood to the site of infection, revealed significantly reduced (p < 0.001) levels at the site of Mtb infection in both PTB (BAL cells) and pleural TB (pleural fluid cells) (Figure 3b,c), while there was no difference in LL-37 mRNA comparing PBMCs to lymph node tissue from patients with LNTB (Figure 3d).