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The presence of alpha 2-macroglobulin (alpha 2M) was detected with the avidin-biotin technique in more than 20-yr-old paraffin blocks from human sarcomas. alpha 2M was found mainly in the cytoplasm of the tumor cells, and almost all tumor cells were positive. This serum glycoprotein, which is a major plasma proteinase inhibitor with a wide specificity, was also shown to be synthesized and secreted by all three cell lines derived from primary sarcomas but was not detected in cultures of the autologous skin fibroblasts. For the detection of alpha 2M in situ and in vitro an antiserum to tumor-associated alpha 2-macroglobulin was used.

Using cytofluorometric single-cell DNA analysis, the pattern of nuclear DNA content was determined in preoperative biopsies from 166 unselected primary adenocarcinomas of the rectum or rectosigmoid. The pattern was aneuploid (AN) in 125 (75%) of the tumours, was aneuploid (AN) in 125 (75%) of the tumours, near-diploid with aneuploid cells (ND-anc) in 26 (16%) and near-diploid (ND) in 15 (9%). The DNA content was not related to tumour stage or degree of differentiation. The clinical course tended to be more favourable in patients with ND tumour than in those with AN or ND-anc pattern. The nuclear DNA content in rectal carcinoma thus can be estimated in preoperative biopsies, and the pattern may serve as a prognostic parameter.

The reaction patterns of eight antibodies directed against blood group substances A, B and H, respectively, against Lewis B antigen, difucosylated carbohydrate antigens (DFCA), gastrointestinal cancer antigen CA 19-9 (GICA), carcinoma-associated antigen CA-50 and CEA, were studied in 68 rectal carcinomas using the avidin-biotin-peroxidase method. A pronounced intratumoral antigenic heterogeneity was revealed for most antigens. It thus became evident that an interpretation based upon small preoperative biopsies would be inaccurate. The overall proportion of positive carcinoma cells, however, did not vary much between larger samples taken postoperatively from different regions of the tumours. The intertumoral antigenic variability was also considerable: nearly all tumours had an individual immunohistochemical profile according to the proportions of positive cells. Heterogeneous staining patterns were also present within metastases, and lymph node metastases from the primary tumour in some cases differed completely from each other. The staining pattern did not correlate with Dukes' stage, and degree of differentiation; the expression of any individual antigen, or several antigens in combination.