Apoptosis during protozoan infection. Gavrilescu L C , and Denkers E Y Infect. Immun. 2003;71:6109-6115 Apoptosis during protozoan infection. From the host perspective, CTL activity and AICD can be viewed as homeostatic, anti-inflammatory responses to protozoan parasite infection that control the spread of infection and resolve the immune response after resolution of the infection. Alternatively, overexpression of type 1 proinflammatory cytokines, nitric oxide, or Fas-FasL may lead to uncontrolled apoptosis, in this situation becoming a proinflammatory response. A switch from a homeostatic response to a pathological response may occur in the course of infection, as when type 1 cytokines act to limit infection but then cause tissue and cellular apoptotic damage.