Distribution of membrane-associated actin in sheep lymphocytes. Functional implications.

Using the DNAase I inhibition assay, we titrated two forms of actin, monomeric (G) and total (G + F) actin of various populations of lymphocytes in adult and fetal sheep. Lymphocytes leaving a lymph node always showed higher actin activities than lymphocytes resident in the lymph node at the time of examination. T cells had significantly higher actin activities than B cells. A subpopulation of T cells which is present in the blood but not in the lymph showed much lower activities than total T cell populations in the blood or efferent lymph. Thymocytes showed the lowest actin activities among the lymphoid cell populations examined. A proposal is made that DNAase I inhibitions per cell can be considered as an intrinsic parameter of lymphocyte recirculating abilities.