Australian-German collaborative studies on the immunology of Sarcocystis infections.

This paper reviews a decade of collaborative studies performed between two laboratories in Germany and Australia on the life cycle, pathogenicity and immunology of infections by the cyst-forming sporozoan parasites Sarcocystis spp. in domestic animals. Experimental transmission studies demonstrated that certain parasite species could cause an acute clinical disease in sheep and pigs severely affecting their health, productivity and reproductivity. Despite the high prevalence of infections found in farm animals, few outbreaks of naturally-occurring clinical disease have ever been recorded. Host animals exposed to low levels of infection were found to develop a strong protective immunity against subsequent lethal challenge and clinical disease even though parasites were not completely eliminated nor prevented from further establishment (premunitive immunity rather than sterile immunity). Modern molecular biological techniques are currently being used to examine the parasite antigens and host immune responses involved in the acquisition of the protective immunity.     

Antineutrophil cytoplasmic antibodies in IgA nephropathy and Henoch-Sch?nlein purpura.

The frequency, isotype, and specificity of antineutrophil cytoplasmic antibodies were investigated in a cross-sectional study of 100 patients with IgA nephropathy and 30 children with Henoch-Sch?nlein purpura. Two of the patients with IgA nephropathy had high titres of antineutrophil cytoplasmic antibodies which were of IgG isotype and confirmed as antimyeloperoxidase antibodies in solid-phase ELISA and inhibition experiments. Antineutrophil cytoplasmic antibodies were not detected in the children with Henoch-Sch?nlein purpura and none of the patients in either group had IgA antineutrophil cytoplasmic antibodies. A further 20 IgA nephropathy and 10 Henoch-Sch?nlein purpura patients were studied longitudinally in different clinical phases at 4-monthly intervals over a 2-year period. None of these patients had or developed antineutrophil cytoplasmic antibodies. We conclude that IgA antineutrophil cytoplasmic antibodies are not involved in the vasculitis of Henoch-Sch?nlein purpura or in the pathogenesis of glomerular injury in IgA nephropathy. The detection of IgG antimyeloperoxidase antibodies in a small minority of IgA nephropathy patients extends the spectrum of diseases associated with autoimmunity to this antigen but is of uncertain significance.