Upregulation of ICAM-I by Plasmodium falciparum: in vitro and in vivo studies.
OBJECTIVE
To monitor the expression of intercellular adhesion molecule I (ICAM-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 mononuclear 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 after treatment (Rio Branco, Acre, Brazil).


RESULTS
ICAM-I expression increased from 15% to 375% after four hours of stimulation. When sICAM-I was analysed in the plasma of 122 patients with P falciparum or Plasmodium vivax malaria by enzyme immunoassay, significant increases were found. These were more pronounced in patients with P falciparum malaria, compared with healthy controls, and with the same patients four weeks after treatment.


CONCLUSIONS
ICAM-I expression may also be upregulated in human macrophages by exogenous Plasmodium antigens as well as by cytokines during the acute phase of malaria. sICAM-I concentrations are downregulated after treatment, probably caused by the absence of circulating Plasmodium antigens.
Graninger
W
W
Department of Internal Medicine I, University of Vienna, Austria.
Prada
J
J
Neifer
S
S
Zotter
G
G
Thalhammer
F
F
Kremsner
P G
PG
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D000953:Antigens, Protozoan / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D018950:Lipopolysaccharide Receptors; D008264:Macrophages / Q000276:immunology*; D016778:Malaria, Falciparum / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology*; D015854:Up-Regulation
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000953:Antigens, Protozoan; D015815:Cell Adhesion Molecules; D018950:Lipopolysaccharide Receptors; D018799:Intercellular Adhesion Molecule-1