Functional relationship of macrophages and basophils to the thymus gland.

Human thymus epithelium, depleted of thymocytes and macrophages by means of organ culture, was used in chemotaxis experiments with peripheral blood cells. Such cultured thymus epithelium can attract specifically macrophages and basophils. T-lymphocytes were attracted only by short-term (8 day) cultured thymus tissue which still retains some of the original macrophage population. Thymic macrophages formed rosette structures with thymocytes. In other experiments 'activated' rabbit macrophages had the capability to destroy thymocytes, whether autochthonous or allogeneic. The possible role of macrophages and basophils in thymus function is discussed.