ABSTRACT
Host effector cells, the terminators of pathogenic microorganisms in the host defense system, are strategically placed in the body. Macrophages are found in the lungs, liver, spleen, lymph nodes, and peritoneum. The parasitic yeast-form of P. brasiliensis grown in McVeigh-Morton (McV-M) broth yields preparations of yeast cells consisting primarily of single and double cell units, which are required for in vitro studies with macrophages, so that sequential events can be recorded. When Paracoccidioides brasiliensis enters the host it has to interact with many of these effector cells and resist their microbicidal mechanisms. The naturally infective form of the saprophytic stage of P. brasiliensis is considered to be various small survival structures formed under stress conditions, e.g., arthroconidia, chlamydoconidia, and conidia. NK-cells are nonphagocytic effector cells that are cytotoxic for allogeneic cells, syngeneic tumor cells, virus infected syngeneic cells and maybe some protozoan parasities.
