Use of the immune adherence hemagglutination test for titration of breast cancer patients' sera cross-reacting with purified mouse mammary tumor virus

92 sera from patients with breast cancer, 42 sera from patients with neoplastic diseases other than breast cancer and 59 sera from apparently healthy women were examined by means of the immune adherence hemagglutination (IAHA) test using purified mouse mammary tumor virus (MMTV) from RIII mouse milk. It was found that 36.4% (35/96) of the sera from breast cancer patients, 7.1% (3/42) of the sera from patients with other neoplastic diseases and 5.1% (3/59) of the sera from apparently healthy women showed a positive reaction. Among the IAHA positive sera from breast cancer patients, 82.9% (29/35) showed a titer of more than 1:16. On the other hand, none of the positive sera from patients with cancers other than breast cancer showed a titer of more than 1:16. The sera from 4 breast cancer patients, which showed a positive reaction with RIII MMTV in the IAHA test, we tested to examine the specificity of the reaction by using milk samples from sources other than RIII mice, including C57BL mice, dogs, cattle and humans. None of the 4 sera showed a positive reaction with milk samples from sources other than the RIII mouse.