The macrophages as an effector cell in Giardia lamblia infections.

Direct and antibody-dependent, cell-mediated cytotoxic responses exhibited against Giardia lamblia trophozoites by peritoneal macrophages of infected animals were studied. On first exposure, the infection persisted for 30 days and peak cytotoxic responses were noticed on the 20th day post infection. In reinfected animals, peak response was on 10th day and these animals were capable of clearing the infection much faster compared with animals infected for the first time. Macrophages in Giardia infection, therefore, seem to play an important role in providing resistance to infected animals as evident from significant augmentation of their cytotoxic responses in the infected animals.