We examined the immunogenicity of various connective tissue
proteins in patients with chronic onchocercal
dermatitis and the effect of filarial
proteases on this host-parasite interaction. Sera from patients with
onchocerciasis reacted strongly with cuticular
collagens from filarial parasites and with mammalian
laminin. Some sera also contained
antibodies to
elastin and
collagen type IV, but none reacted with
collagen types I-III or
fibronectin. This pattern of reactivity was characteristic for
onchocerciasis: sera from patients with
mansonellosis reacted strongly with
collagen type IV but only weakly with
laminin. Reactivity with mammalian
laminin or
collagen could not be absorbed with cuticular
proteins from filarial worms and vice versa. Digestion fragments of
laminin treated with filarial
proteases retain
antigenic determinants recognized by sera from patients with
onchocerciasis. In contrast,
proteases from Onchocerca volvulus adults and microfilariae drastically decreased the reactivity of the same sera with
collagen type IV. These results indicate that filarial
proteases may contribute to the pathogenesis of chronic onchocercal
dermatitis, directly, by enzymatically destroying connective tissue of the skin, and indirectly, by triggering autoimmune responses to self-determinants on connective tissue
proteins that are normally hidden within the supramolecular structure of the extracellular matrix complex.