Guinea pig erythrocyte rosette formation as a nonspecific cell surface receptor assay in the cat

Abstract

SUMMARY The specificity of guinea pig erythrocyte (gpe) rosettes for feline peripheral blood lymphocytes was studied. Of the gpe rosette-positive cells from peripheral blood, 54% were monocytes, 29% were granulocytes, and only 17% were lymphocytes. Results were similar for rosettes incubated at 4 C and those incubated at 37 C. Mononuclear cells separated with polyvinylpyrrolidone-coated silica formed fewer monocyte rosettes (49%) and more granulocyte rosettes (34%) than did cells separated with sodium diatrizoate-Ficoll (60% monocyte rosettes and 18% granulocyte rosettes), whereas the percentage of lymphocyte rosettes was similar for both media. Mononuclear cells suspended in Eagle's minimum essential medium had a higher percentage of monocyte rosettes (75%) and a lower percentage of granulocyte rosettes (12%) than did cells suspended in RPMI 1640 medium (59% monocyte rosettes and 27% granulocyte rosettes). The percentage of lymphocyte rosettes was similar in the 2 media. Two sequential 45-minute plastic adherent cell depletions decreased monocyte rosettes to 51% and increased lymphocyte rosettes to 23% compared with 63% monocyte rosettes and 12% lymphocyte rosettes before adherent cell depletion. The granulocyte rosettes were unchanged by plastic adherent cell depletion. The percentage of rosette-positive cells (9%) was not significantly affected by incubation at 4 C or 37 C, cell separation with polyvinylpyrrolidone-coated silica or lymphocyte separation medium, or suspension in Eagle's minimum essential medium or RPMI 1640 medium. Plastic adherent cell depletion decreased the percentage of rosette-positive cells. Feline thymocytes were 38% to 80% gpe rosette-positive and a feline leukemia virus-infected lymphoblastic cell line (F422) was 88% gpe rosette-positive. Although a high percentage of thymocytes and cultured feline leukemia virus-infected lympho-blasts may be gpe-receptor positive, gpe receptors were not specific for peripheral blood T cells in the cat.