Immunohistological Studies on Human αlactalbumin in Mammary Glands of Various Clinical States

Abstract

Human αlactalbumin (LA) was isolated from fresh milk of a lactating woman, and anti-LA serum was obtained from the immunized rabbit. To detect the localization of LA in human mammary tissues, an indirect immunohistological method using this anti-LA serum has been devised. For the observation of LA, the peroxidase anti-peroxidase method was superior to the peroxidaselabelled antibody method on serial sections of the secreting mammary tissue. The immunohistological findings in paraffin section from the routinely formalin-fixed tissue were almost the same as those in paraffin section of the same, Zamboni-fixed tissue. As LA antigen was proved to be relatively stable against the routine histological method, many of clinical samples could be retrospectively applied to the present investigation.
The reaction products of the immunohistological method for LA antigen were detected in functionally active cytoplasma of the mammary parenchymal cells and on secretory materials within the mammary ductules and ducts. They revealed the following staining patterns; reticular, focal, peripheral and membrane-like. LA antigen could never be observed immunohistologically in any other sites than the mammary parenchyms in the present observations on many clinical samples including the placental tissue.
The positivity rates of LA antigen in the present materials were as follows: Resting state of adult normal mammary tissue 0/1, secreting, focally hyperplastic normal mammary glands surrounding the foci, of mammary dysplasia and carcinoma 18/18, mastitis 0/2, gynecomastia 0/2, mammary dysplasia 9/136, mammary fibroadenoma 8/66, and mammary carcinoma 10/113. LA antigen revealed mainly reticular, apical and/or lateral cytoplasmic membranelocated membrane-like staining patterns in the secreting normal mammary glands, but various staining patterns of LA antigen were observed in the malignant mammary tumors, in which the LA-positive tumor cells were spottedly detected, on the cases of mammary carcinoma, there was no definite relationship between the positivity of LA antign and the histological type and grade of differentiation of tumors, although the positivity in the cases of Tnm stage IV orof grade III differentiation appeared to be somewhat higher than the cases of earlier stages or of lesser gradings of differentiation. LA antigen was detected in the metastatic focus of mammary adenocarcinoma in the lymph nodes (1/13). Although the positivity was very low, the positive finding of LA antigen in the metastatic focus may be useful for the evaluation of primary site of malignant tumors.