CELL-ADHESION MOLECULES EXPRESSED BY ACTIVATED EOSINOPHILS IN ONCHOCERCA-VOLVULUS INFECTION

Cell-adhesion receptors mediate the interaction between host effector cells and cellular or multicellular targets, including opsonized paras ites. Our recent finding of a deposition of plasma proteins, including fibronectin, on the surface of infective larvae of the helminthic par asite Onchocerca volvulus led us to investigate the possible expressio n of cell-adhesion molecules (CAM), particularly fibronectin receptors , on eosinophilic granulocytes from persons infected with O. volvulus. Immunofluorescence analyses showed that freshly isolated eosinophils strongly expressed the beta 2-integrin CR3 and exhibited to a lower de gree CR4 and the integrin-associated carbohydrate determinant Le(x), a s well as antigen p24 (CD9). Eosinophils exposed to the eosinophilacti ve cytokines recombinant human interleukin 3 (rhIL-3) and granulocyte/ macrophage colony-stimulating factor (rhGM-CSF) in addition to CR3, CR 4, and CD9 expressed the beta 1-integrins VLA-4 and to a lesser extent VL-5 (both fibronectin receptors) as well as the intercellular adhesi on molecule ICAM-1. Low-level expression of these adhesins was also ob served on eosinophils cultured in the presence of these interleukins o n confluent fibroblasts. The presence of VLA-4 as well as VLA-5 on act ivated eosinophils was confirmed by demonstration of the formation of immune rosettes using antibody-coated microspheres and by their attach ment to fibronectin-coated surfaces. These results indicate the possib ility of an involvement of previously unidentified antibody- and compl ement-independent mechanisms in cellular interactions with the parasit e O. volvulus.