Effect of soluble antigen on the ellipsoid-associated cells of the chicken's spleen.

The ellipsoid-associated cells (EAC) localize on the surface of the ellipsoid. They bind the IV injected horseradish peroxidase (HRP) and bovine serum albumin (BSA), migrate to the red pulp and then enter the systemic circulation. After protein injection, the number of white blood cells increased above the normal level. The highest number of white blood cells occurred between 4 and 6 hr after HRP injection. In this period, the cell enhancement resulted in HRP-positive mononuclear cells which might come from the spleen. This cell population may vary in size and number in the blood and may be identical with the dendritic cell of the chicken. The other type of blood mononuclear cell is histologically identical with the classical monocyte endogenous peroxidase positive type and their number is lower than that of the former. This type of monocytic (MN) cell could be of bone marrow origin.