The clinical significance of radioimmunological determination of Tissue Polypeptide Antigen (TPA) has been studied on patients with breast cancer (n = 376), on "normal subjects" (n = 92), on benign diseases of the breast as well as on patients with inflammatory diseases (n = 98). TPA levels were elevated (120 U/l or higher) in the group with inflammatory diseases in 68% and in the group with breast cancer (stage IV with progression of disease) in 85%. In all other groups (healthy controls, benign diseases of the breast, breast cancer before operation, breast cancer stage I (NED), breast cancer stage II and III (NED), and breast cancer stage IV (PR/CR), TPA was higher only in 5-22%. TPA determinations seem not to be very useful for diagnostic purposes in breast cancer, but it can be regarded as suitable for monitoring proliferative processes in advanced breast cancer. Limitations result from lack of tumor specificity of the proliferation marker TPA. So far, follow-up studies after mastectomy in breast cancer and in patients with advanced breast cancer under chemotherapy have shown that CEA and TPA are concordant. There is no cross reactivity between CEA and TPA. The main component of the labeled tracer has an isoelectric point of 4.4 but there is some impurity in the tracer as it was shown in chromatofocusing.

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Lymphocytes from seven patients with malignancies, from seven patients with non-malignancies, and from five healthy persons were incubated with 125I-labeled MBP. Binding of MBP of lymphocytes was monitored from 0.5 to 20h. The binding ranged from 4 to 7% of the total MBP present and remained fairly constant during the first 4h of incubation. It dropped considerably at 20h. Mean percentages of MBP binding were lower in cancer patients than in persons without malignancies. After incubation, the supernates were examined by gel electrophoresis. The electrophoretic pattern was similar in comparing groups with different diagnoses. A considerable loss of MBP in the terminal supernatant (20h) was found. When tested in the electrophoretic mobility test (EM test) with stabilized erythrocytes, supernatant derived from cancer patients produced a somewhat higher mean slowing effect than did superntes from other patients and controls.