Demonstration of thymus-leukemia (TL) antigens on mitochondria of lymphoid cells by immunoelectron microscopy.

The presence of thymus-leukemia (TL) antigens on the surfaces of mitochondria isolated from TL+ cells, e.g., RADA 1 leukemia cells, and TL+ normal thymocytes, has been directly demonstrated by immunoelectron microscopy. Reagents used were TL alloantiserum and a hemocyanin conjugate of rabbit antibody to mouse IgG. No hemocyanin labeling was observed on mitochondria obtained from TL- cells, e.g., thymocytes of TL- strains, splenocytes of either TL+ or TL- strains, and TL- leukemia cells. The concurrence of TL antigens on the plasma and mitochondrial membranes was shown by the ability of intact cells to absorb all reactivity toward mitochondria.