Inhibition of neutrophil functions by scrapie prion protein: description of some inhibitory properties

The effect of scrapie prion protein (PrP) either in the native or in the denatured form was studied on in vitro responses of human neutrophils. Incubation of neutrophils with native PrP caused an inhibition of their aggregation induced by cytochalasin B. Moreover, the denatured form was in itself a strong aggregation inducer. When evaluating the effect on generation of neutrophil superoxide anion (O2) we found that neutrophils released O2 in response to the denatured from only but the native form was ineffective. Similarly, neutrophil discharge of beta-glucuronidase which represents the azurophilic granule marker was stimulated in a dose-dependent form by the denatured PrP 27-30 whereas the native form was almost completely devoid of any activity. These results indicate that several aspects of neutrophil function can be altered by the native form of prion protein PrP 27-30. This might be responsible for the impaired phagocytic cell activity explaining, at least in part, the absence of any inflammatory reaction during scrapie infection.