Masking of receptors for sheep erythrocytes on human T-lymphocytes by sera from breast cancer patients.

Sera from 140 breast cancer patients and 38 controls were tested for their ability to inhibit sheep erythrocyte (E) rosette formation by normal, allogeneic lymphocytes. Inhibition of rosette formation by greater than 20% was found with 65% of stage I sera, 91% of stage II sera, 56% of stage III sera, and all stage IV sera. In contrast, only 13% of control sera was inhibitory. The inhibitory factor was found to bind to only a proportion of T-lymphocytes and could be removed from these lymphocytes by mild proteolytic digestion or extended washing. Examination of the properties of the inhibitory factor indicated that it differed from other substances that reportedly inhibited E-rosette formation.