[Effect of 4B3 monoclonal antibody on the experimental Cryptococcus neoformans infection].

Introduction: frequent relapses and high lethality of criptococcosis has encouraged the search for new therapeutic strategies.

Objectives: to evaluate the effect of the monoclonal antibody 4B3 on the cryptococcal infection in Balb/c mice.

Methods: the kinetics in serum concentration of the studied monoclonal antibody was determined for intraperitoneal administration (500 microg) by quantitative sandwich ELISA. In order to assess its protective capability, were administered 500 microg of 4B3 and innoculated 2 x 10(22) cells/mL of Cryptococcus neoformans. The survival of mice was recorded and the yeast dissemination to the main target organs was evaluated. Macrophages P338.D1 cell lines were used to measure the effect of the monoclonal antibody 4B3 on the phagocytosis and lysis of the microorganism.

Results: the used dose helped to keep high values (38 microg/m) of 4B3 in serum for at least 46 days. It was found that the monoclonal antibody does not give protection, which makes the microorganism dissemination possible, along with the reduction in the survival of mice. Finally, the phagocytosis test showed that 4B3 increased the phagocytic activity of macrophages without any fungicidal effect.

Conclusions: the monoclonal antibody 4B3 stimulates C. neoformans phagocytosis by macrophages without fungicidal effect, thus favoring yeast dissemination and decreasing the survival of mice due to cryptococcal infection