Effects of heterologous antineutrophil antibody in the cat

Rabbit anti-cat neutrophil serum was injected intraperitoneally into cats to study its effects on blood neutrophil numbers, on development of neutrophils in bone marrow, and on the fate of circulating and developing neutrophils. There was a significant difference (P less than 0.05) in curves of blood neutrophil numbers between antineutrophil serum (ANS)- and normal rabbit serum (NRS)-injected cats; neutrophil counts tended to decrease in ANS-injected cats, whereas a transient increase in counts occurred in NRS-injected cats. Significant left shifts (P less than 0.05) were present in ANS-injected cats, but absent in NRS-injected cats. Toxic morphologic changes were noted in blood neutrophils in all ANS-injected cats. Significant bone marrow changes (P less than 0.05) occurred in ANS-injected cats, but were absent in NRS-injected cats. Myelocyte percentages of the granulocyte marrow population increased during the time that segmented neutrophil percentages decreased. In ANS-injected cats, the percentage of cells in the mitotic pool (myeloblasts, promyelocytes, myelocytes) significantly increased (P less than 0.05), with a corresponding significant decrease (P less than 0.05) in the postmitotic pool (metamyelocytes, bands, segmented neutrophils). Aspirated bone marrow smears (Wright's stain) revealed marrow macrophages containing phagocytized neutrophil bands and segmented neutrophils. Sections of liver obtained after cats were necropsied revealed neutrophil phagocytosis by Kupffer's cells, but neutrophil phagocytosis was not demonstrated in other tissues examined.