IMMUNOELECTRON MICROSCOPIC STUDIES ON THE SPECIFIC ADHESION OF TRYPANOSOMA-CONGOLENSE TO CULTURED VASCULAR ENDOTHELIAL-CELLS

Bloodstream forms of Trypanosoma congolense were cocultivated in vitro with vascular endothelial cells. The trypanosomes adhere specifically to the endothelial surfaces of the anterior part of their flagella, a s shown by scanning and transmission electron microscopy. The interact ion between parasite and host cell is very tight, and frequently the a ccumulation of endocytotic vesicles near the contact site is observed. Immunoelectron microscopy revealed a compound distributed over the to tal surface of the trypanosomes and reacting with antibodies against t he beta 1 integrin chain, but no reaction was found with anti-alpha 1 or anti-alpha 2 antibodies. Integrins are typical adhesion molecules a nd are now shown to be present at the surface of T. congolense by elec tron microscopy and by immunofluorescence. A direct participation of t his substance in the specific adhesion to endothelium, however, could not be proven. (C) 1994 Academic Press, Inc.