Pathology of reversed passive Arthus reaction in the chicken.

Sequential study of gross and microscopic changes in the chicken skin revealed that it was possible to induce a reversed passive Arthus reaction in 14- to 20-week-old chickens, using bovine serum albumin and anti-bovine serum albumin. However, high doses of immune reactants were required to elicit lesions of optimal intensity. The lesions were characterised by erythema, oedema, and the formation of thrombi in the vessels of the superficial dermis. Thrombosis, caused by the adherence of thrombocytes to vascular endothelium, induced widespread necrosis and haemorrhage. The inflammatory changes, which were confined to the deep dermis, included a necrotising vasculitis with infiltration of heterophils, monocytes and basophils. Phagocytosis of carbon particles by heterophils and basophils appeared to be sensitisation-dependent. The reaction was also characterised by the development of perivascular lymphoid foci. The findings indicate that in chickens the thrombocyte appears to be the principal cell involved in the induction of tissue damage.

Pathology of the active Arthus reaction in the chicken.

It was possible to produce an active Arthus reaction in chicken skin which resulted in gross and microscopic lesions. Histologically, the reaction was predominantly thrombotic in nature and restricted to the upper dermis. The thrombi appeared to develop as a consequence of immune complex deposition with adherence and aggregation of thrombocytes at the vascular endothelium. Thrombosis induced widespread necrosis and haemorrhage and vasculitis occurred in the lower dermis. Up to four hours after inoculation, the cell population comprised an infiltration of heterophils, monocytes and basophils, suggesting an immediate hypersensitivity reaction. This was followed by an Arthus type reaction for four to 12 hours involving both heterophils and monocytes. A characteristic feature was the development of early perivascular lymphoid foci. After 12 hours the reaction resembled a delayed hypersensitivity. The use of colloidal carbon suggested that whereas phagocytic activity of the heterophils and basophils appeared sensitisation dependent, that of thrombocytes and monocytes was independent of it. The findings indicate that in the Arthus reaction in the chicken the thrombocyte appears to be the principal cell producing tissue damage by thrombosis. A comparison was made with the active Arthus reaction in the rabbit.

Demonstration of the phagocytic activity of chicken basophils in the reversed Arthus reaction using colloidal carbon.

Chicken basophils showed phagocytosis of carbon particles in reversed passive Arthus reaction, induced in the skin. Heterophils, monocytes and thrombocytes also contained carbon particles, but eosinophils revealed them only occasionally. The findings suggest that basophils may share phagocytic properties with other cells under immunological stimulus.