Lymphocyte emperipolesis revisited. I. Development of in vitro assay and preliminary characterisation of the lymphocyte subpopulation involved.

A surprisingly high proportion of antibody (IgG) sensitized Chang liver cells apparently contained one or more intracytoplasmic human peripheral blood lymphocytes following a period of contact at 37°. Since various technical factors were found to influence this phenomenon of lymphocyte `emperipolesis', optimum conditions were selected for use in a standard quantitative assay. Lymphocytes from normal individuals varied considerably in their ability to participate in emperipolesis; an observation which suggested that a particular lymphocyte subpopulation may be involved. Preliminary characterization of emperipoletic cells indicated that they are Fc receptor bearing, non-T lymphocytes. The significance of these findings in relation to immune mechanisms is discussed.