Adaptive immune responses (it takes them days to respond to a primary invasion) such as infection by any pathogen, lead to production of antibodies and cell-mediated responses which recognize foreign pathogens and destroy them as a function of specific immune cell types. The response to a second round of infection is often more rapid than to the primary infection because of the activation of memory B and T cells. These responses are mediated by signals such as lymphokines, cytokines and chemokines produced by various cells and these in turn stimulate cells of the immune system. .
