Increased proportion of Fc gamma and Fc mu positive T-lymphocytes following treatment with neuraminidase.

Membrane receptors for IgG (Fc gamma) and IgM (Fc mu) were assessed on isolated peripheral blood T-lymphocytes by rosette formation with ox-RBC coated with rabbit IgG or IgM antibodies. The mean percentage of Fc gamma and Fc mu rosettes on freshly separated T-cells was 19% (+/- 6% SD) and 4% (+/- 1% SD), respectively. These values increased significantly to 40% (+/- 9%) for Fc gamma and 34% (+/- 8%) for Fc mu after preincubation of the lymphocytes with Neuraminidase. The proportion of Fc mu, but not of Fc gamma, rosettes increased to 44% (+/- 8 SD) after overnight incubation at 37 degrees C, and less markedly after incubation for 45m at 37 degrees C (29% +/- 7). Fc gamma and Fc mu rosette formation, with or without neuraminidase, was specifically inhibited by human IgG or IgM. These findings suggest (1) that hidden receptors can be demonstrated on T-lymphocytes after Neuraminidase treatment which, in the case of Fc gamma, cannot be revealed by other means, and (2) that the proportion of T gamma lymphocytes in the peripheral blood is higher than generally believed.