Summary
In rabbits and cats Congo red administered intravenously causes severe thrombocytopenia and ultrastructural alterations of platelets and leucocytes, similar to those produced by some fatty acids and endotoxin. Transient leucopenia is followed by leucocytosis. In contrast, incubation of Congo red in citrated blood or platelet rich plasma has no effect. Therefore, an indirect mechanism is postulated to explain the in vivo effect of Congo red.
