Monoclonal antibody which agglutinates erythrocytes from cancer patients

B5 tumour marker and urine cytology in diagnosis and follow-up of transitional cell bladder cancer

The correlation between a new tumor marker, B5, and tumour behaviour in bladder cancer was recorded and an assessment made of the value of combining the B5 test with urine cytology for predicting the presence of tumour. The study group included 57 new patients, of whom 32 were B5 positive at diagnosis and were well marked by B5 on follow-up. There were no false positive shifts in new patients who became free of observable tumour, whilst 1 of 13 patients with persistent disease showed a false negative shift. When the findings from 199 cystoscopies were compared with the results of B5 and urine cytology, B5 was found to improve the prediction of recurrent tumour over cytology alone. Moreover, a high incidence of occult malignancy (7/19) was found in patients where cystoscopy had failed to show recurrence but whose combined marker results were both positive.

Exposure of cryptantigens on erythrocytes in patients with breast cancer

One hundred thirty-two patients with breast cancer were examined for exposure of cryptantigens on their erythrocytes (RBC) using a lectin panel consisting of Arachis hypogaea and Glycine soja. Eight had exposed cryptantigens; of the eight, five were classified with additional lectins as T-polyagglutination type and three as Th-polyagglutination. A control group of 300 healthy blood donors had no exposed cryptantigens on their RBC. These findings could not be correlated with the staging of the tumor, extension of metastases, or positive estrogen or progesterone receptors of malignant tumor cells. Only one study has been found that describes the incidence of agglutination of erythrocytes from cancer patients using a monoclonal antibody, which detected an epitope on the RBC from cancer patients and was considered to be distinct from the antigen bound by naturally occurring anti-T. Studies have been made describing polyagglutinable sites on breast cancer tumor cells, where there was a much higher incidence. This discrepancy can be explained either by a difference in the methods used to search for cryptantigen exposure on the various types of cells, or by the existence of a different mechanism, which causes the exposure of cryptantigens on RBC as opposed to malignant breast tumor cells.

A new indicator of human malignant tumour

In haemagglutination tests we have found that the monoclonal antibody B5 discriminates between erythrocytes from patients with malignant cancer (total 386; greater than 80% B5 positive) and individuals with no known tumour (total 247; less than 20% B5 positive). The B5 antigen detected on intact erythrocytes is a tightly bound surface component which does not appear to be derived from the plasma. The B5 antigen is not T, Tn, Ca1, CEA or the Forsmann antigen; nor is it related to any of the major blood group antigens. Abnormal levels of surface B5 are found on erythrocytes from patients with a great diversity of tumours and this fact presents B5 as an indirect marker of malignancy. Successful eradication of tumour is associated with a switch from positive to negative B5 haemagglutination. We believe that B5 is a valuable addition to the few useful tumour markers already employed for monitoring tumour status.