The latex particle adherence (LPA) assay for detection of leukocytes with adhesive surface properties.

A new, simple, and rapid in vitro assay has been developed for identification of adherent and nonadherent leukocytes. The assay is based on adherence of latex (polystyrene) particles to the cell surface. Using the latex particle adherence (LPA) assay, the percentage of adhesive leukocytes has been determined in human peripheral blood mononuclear preparations and in the lymph nodes, thymus, bursa of Fabricius, spleen, and bone marrow of mouse, chicken, and rat origin. The highest proportion of LPA-positive cells was found in peritoneal exudate, bone marrow, and spleen, the lowest proportion, in thymus and bursa of Fabricius. LPA-Positive cells in human peripheral blood mononuclear preparations were identified as surface immunoglobulin-positive lymphocytes nonrosetting with sheep red blood cells. LPA-Positive cells in peritoneal exudate were identified as macrophages. Incubation of leukocyte suspensions on polystyrene petri dishes or nylon wool columns reduces substantially the percentage of LPA-positive cells in the nonadherent fraction. The LPA assay seems to be a method of choice for establishing the relationship between adhesiveness of the cell surface and other cell membrane markers on a single-cell level.