Enhancement of leukocyte membrane receptor expression after mechanical agitation.

Granulocyte and lymphocyte suspensions were exposed to slight mechanical agitation for 30 s on a tube mixer before being examined for membrane receptors by rosette techniques. Agitation caused an increase in the proportion of granulocytes bearing receptors for sheep erythrocytes (E-R), for the Fc portion of IgG (Fc gamma-R), and for C3b (C3b-R), and of lymphocytes bearing the Fc gamma-R. The proportion of E-R-bearing lymphocytes was not enhanced, with the exception of the 'early' or 'active' E-R-bearing cells. The increase in rosette formation was specific, i.e. rosette formation with ox or rabbit E was not induced by agitation. The increased proportion of membrane receptors was not associated with an increase in granulocyte phagocytosis of preopsonized zymosan particles, as measured by chemiluminescence. Membrane perturbation thus probably increases the availability of surface receptors.