Natural cytotoxicity of blood mononuclear cells from normal subjects and patients with Hashimoto's thyroiditis against normal thyroid cells.

Natural cytotoxicity of human blood mononuclear cells against dog thyroid cells grown in monolayer was investigated. Cytotoxicity was assessed as specific release of 51Cr from Na51CrO4 labelled thyroid cells. The effector cells were unfractionated blood mononuclear cells prepared by Hypaque-Ficoll gradient centrifugation. Killing of dog thyroid cells by peripheral blood mononuclear cells from normal subjects was demonstrated. This was time and effector: target cell ratio dependent. Killing by peripheral blood mononuclear cells from patients with Hashimoto's thyroiditis was similar to that for normal subjects although increased killing was demonstrated in 2 patients and decreased killing in 2 patients. A possible role of natural cytotoxicity against thyroid cells in thyroid autoimmunity is discussed.