Large mononuclear (veiled) cells like 'Ia-like' membrane antigens in human afferent lympn.

Studies were done to see whether large mononuclear cells in human afferent lymph possess cytoplasmic veils or Ia-like antigens on their surface. Small numbers of veiled cells were seen in lymph from five subjects: one with post-phlebitis oedema, one with trophic ulcers of the legs, one with common variable immoglobulin deficiency, and two control subjects. They were not seen in afferent lymph from two other patients with oedema of the legs, and one control subject. Only occasional large mononuclear (veiled) cells formed rosettes with IgG-coated erythrocytes, and they did not attach to glass after overnight culture. They had a distinctive nuclear structure and fluorescent antisera showed that their membranes and veils possessed large amounts of 'Ia-like' antigens. They did not have surface immunoglobulin or a monocyte membrane antigen. It was concluded that the membrane and nuclear structure of human large mononuclear (veiled) cells is in keeping with the possibility that they are derived from Langerhans' cells in the skin, and that they can become interdigitating cells in lymphoid tissues. It is suggested that these cells have an important role in the transport of antigens from the skin and the stimulation of T lymphocytes in lymphoid tissues.