In recent years, our activities in in vitro and in vivo models (Plasmodium berghei in mice), have been expanded to cover factors affecting malarial infection susceptibility due to exposure to environmental toxicants including metals (i.e. arsenic, mercury, and cadmium) and pesticides (organophosphate and paraquat). We are interested in the modification of immune function especially the roles of M3-cholinergic muscarinic receptors present in the lymphocytes. Furthermore, we are also interred in immune system and brain functions.