The presence of immunosuppressive 'p15E-like' factors in the serum and urine of patients suffering from malign and benign breast tumours.

Certain types of tumours are capable of producing factors inhibiting mononuclear phagocyte chemotaxis which may contribute to defects in immunosurveillance. In head and neck cancer these factors are said to be related to the retroviral protein p15E. This study examines the presence of p15E-like factors in serum and urine of patients with malign and benign breast tumours. Thirty patients with breast cancer, 29 patients with benign breast masses, and 28 healthy controls were tested blindly with the monocyte polarization assay, using N-formyl-methionyl-leucylphenylalanine as chemo-attractant. The low molecular weight fractions prepared of sera of the malign tumour patients inhibited the monocyte polarization significantly (mean inhibition 34%, s.d. = 12) compared with those of benign tumour patients (15%, s.d. = 7) and of controls (14%, s.d. = 6). The observed inhibitory effects on the monocyte polarization could be compensated by MoAbs reactive to p15E-related antigens. The mean difference between the polarization inhibition with and without anti-p15E adsorption (the 'p15E-like factor-induced inhibition') was 25% (s.d. = 13) in the breast cancer group, compared with 7% (s.d. = 5) in the benign tumour patients and 5% (s.d. = 4) in the healthy control group. Surgical removal of the tumours resulted in a restoration of the monocyte polarization in 20/23 (87%) patients of the breast cancer group. Results testing preoperative urine samples correlated well with those of corresponding sera. These data give additional support to the concept that tumour-derived p15E-like factors are responsible for the inhibitory effect on monocyte chemotaxis in breast cancer patients, and that these factors can be found in serum as well as in urine.