UP-REGULATION OF ICAM-I BY PLASMODIUM-FALCIPARUM - IN-VITRO AND IN-VIVO STUDIES

Aims-To monitor the expression of intercellular adhesion molecule I (I CAM-I) in vitro after stimulation of human macrophages with Plasmodium falciparum antigens, as well as the plasma concentrations of soluble ICAM-I (SICAM-I) in vivo in malarial patients. Methods-Human mononucle ar leucocytes were cultured and stimulated for four hours with 300 ng/ ml exogenous P falciparum antigens. CD14 and CD54 (ICAM-I) expression was monitored using flow cytometry. Soluble ICAM-I (s ICAM-I) was also measured in the blood of 122 outpatients with malaria before and afte r treatment (Rio Branco, Acre, Brazil). Results-ICAM-I expression incr eased from 15% to 375% after four hours of stimulation. When sICAM-I w as analysed in the plasma of 122 patients with P falciparum or Plasmod ium vivax malaria by enzyme immunoassay, significant increases were fo und. These were more pronounced in patients with P falciparum malaria, compared with healthy controls, and with the same patients four weeks after treatment. Conclusion-ICAM-I expression may also be upregulated in human macrophages by exogenous Plasmodium antigens as well as by c ytokines during the acute phase of malaria. sICAM-I concentrations are downregulated after treatment, probably caused by the absence of circ ulating Plasmodium antigens.