TRYPANOSOMA CRUZI: IMPAIRMENT OF ANTIGENIC PRESENTATION IS RELATED TO PARASITE POPULATION

C. ALBA SOTO, G.A. MIRKIN AND S.M. GONZÁLEZ-CAPPA

Salzburgo, Austria

Congreso; XI Internatinal Congress on Protozoology; 2001

International Society of Protozoology

We analysed whether antigenic presentation differs between two T.cruzi populations with opposite immunobiological behaviour. Expression of Mayor Histocompatibility Complex class II (MHCII) and co-stimulatory molecules (CD80, CD86, CD40 and CD24) was determined by flow cytometry in Antigen Presenting Cells (APC) from C3H/HeN mice infected with T.cruzi RA strain (highly virulent/pantropic) and K98 clone (weakly virulent /myotropic). During the acute phase of infection no alterations were detected in the expression of co-stimulatory molecules. However, differences in the MHCII expression were found: similar values were registered in the splenic dendritic cells from controls and K98-mice (81.6% and 84.0%) vs. 4.0% in cells from RA-mice (P<0.001). RA strain also inhibited peritoneal macrophages (PM) MHCII expression (5.2%) while it was adequately enhanced by K98 (83.7%) (P<0.001). B-lymphocytes from K98-mice showed adequate MHCII expression (89.1%) while those from RA-mice and controls presented similar lower values (55,0% and 52.5%) (P<0.01). The low MHCII expression in RA-mice was independent of the route of inoculation(intradermoplantar/intraperitoneal). During the chronic phase, APC from RA-mice restored the expression of MHCII, reaching similar levels than in K98-mice. Impairment of antigenic presentation during the acute phase of infection could partially account for the higher virulence and lethality proved for RA compared with K98 strain.