IL4 and pneumococcal pneumonia: Thus, as discussed above, given the dual effects (protective and provocative) of IL-17 on the risk of pneumococcal pneumonia, IL-4 (and attenuated production of proinflammatory cytokines by reciprocal inhibition by Th2 cytokines) may play a more important role in determining the risk of pneumococcal pneumonia than IL-17.