Reversible inhibition of mononuclear cell Fc receptors by sera from breast cancer patients.

The number of circulating mononuclear cells (MNC) expressing Fc receptor for IgG (Fc gamma R) was evaluated in 65 breast cancer patients and 37 normal controls by EAG rosette technique. The percentage (mean +/- SD) of Fc gamma + cells in patients (15.5 +/- 7.8) was significantly decreased (p less than 0.001) when compared to controls (20.4 +/- 5.6). The MNC of patients with low basal rosette values recovered their rosetting capacity when incubated in vitro at 37 degrees C. This effect was not related to detectable immune complexes (ICs). Some of the sera of breast cancer patients were also able to reversibly inhibit the capacity to form rosettes by MNC from healthy subjects. Our data suggest that serum factor(s), different from detectable ICs, might be responsible for this inhibiting effect.