Changes in heterophils following antigen injection in immature male chickens.

Eight-week-old Single Comb White Leghorn male chickens were injected intravenously with either .1 mL Brucella abortus (BA) or saline. Blood samples were drawn at 0 and 12 h postinjection and were examined for heterophil numbers and morphology. Differences between numbers of circulating heterophils/mm3 blood were not significant for saline and BA-treated birds at time zero. However, 12 h following injection, heterophil numbers in BA-treated birds were significantly (P less than .05) greater than those in saline-treated birds. Heterophil appearance took two forms: in the first form, granules were small, round, and strongly eosinophilic; in the second form, the granules were large, rod-shaped and more basophilic in staining. These changes indicate the possible involvement of heterophils in the initiation of a humoral immune response through enhancement of some secretory function.