Mechanisms of E-rosette formation by mitogen-stimulated canine lymphocytes

This study examined the mechanisms of E-rosette formation of mitogen-stimulated canine peripheral blood lymphocytes with human and guinea-pig erythrocytes (E). In vitro culture with phytohaemagglutinin-P (PHA-P) increased the number of E-rosette forming cells two- to three-fold within 1 h and ten-fold by 48 h. Mitogen-enhancement of 1 h rosettes occurred via cross-linking of E to lymphocytes by PHA-P. Forty-eight hour rosettes, mediated by natural cytophilic antibodies in serum, resulted from PHA-P-induced increases in the number of cellular Fc receptors for this immunoglobulin. The data obtained in this study indicate that E-rosette formation by resting or mitogen-stimulated canine lymphocytes is neither a reliable nor a specific T-cell marker in this species.