Scrapie-induced changes in the percentage of polymorphonuclear neutrophils in mouse peripheral blood.

A decrease in the percentage of polymorphonuclear neutrophils (PMN) in the peripheral blood of mice appeared 3 days after intracerebral (IC) inoculation with scrapie mouse brain homogenate. Mice inoculated IC with normal mouse brain had PMN percentages similar to those found for uninoculated mice. This difference between normal and scrapie-inoculated mice continued throughout the preclinical phase of the disease. In the clinical phase of the disease, the percentage of PMN was either higher or lower than that found in normals. The factor causing the decrease in PMN percentages was found in the filtrates from 220-, 100-, and 50-nm filters, but not in the filtrates from a 25-nm filter. Sodium periodate treatment of the scrapie brain samples eliminated their ability to cause the decrease in PMN percentages, whereas sodium iodate had no effect. In addition to two genetically different scrapie mouse brain isolates, homogenates of mouse spleen, sheep brain, and sheep spleen from scrapie-affected animals caused a decrease in percent PMN, whereas the corresponding normal tissue homogenates did not.