We have generated three hybridoma-producing monoclonal antibodies (MAs) that show a different spectrum of reactivity to human mammary tissues. Two of these antibodies, 1F10B4 and 1F10G2, recognize a cytoplasmic determinant highly expressed in most of the primary and metastatic breast carcinomas studied, and weakly (or not at all) in normal breast and nonbreast tissues. 3C6F9 detected a surface determinant common to both normal and neoplastic mammary epithelium. Five hundred hybridomas were obtained from the fusion of NS-1 myeloma cells with spleen cells of mice hyperimmunized with the well-characterized human breast carcinoma cell line BT-20. After the initial screenings and clonings, three monoclonal antibodies (1F10B4, 1F10G2, and 3C6F9) showing a restricted range of reactivity were selected for further investigation. These three antibodies recognized a panel of neoplastic mammary cell lines; however, the degree of reactivity could not be correlated to any of the various characteristics of these epithelial cell lines. Moreover, immunofluorescence analysis of acetone-fixed cryostat section showed that 1F10B4 and 1F10G2 recognize the vast majority of the 37 primary and metastatic breast cancers tested, binding strongly to 47% and 67% of them respectively. Only one of the primary carcinomas was not recognized by 1F10B4. On the other hand, these two MAs reacted weakly or not at all with normal breast and nonbreast tissues showing only few focal reactivities with the luminal pole of some ducts of the breast; very weak staining in renal tubular epithelial cells, in few keratinocytes and epithelial cells lining some sebaceous glands in the skin; and a moderate staining in biliary ducts of the liver. All mesenchymal structures including smooth and striated muscle tissues, lymph nodes, and connective tissue were negative. On the other hand, 3C6F9 recognized a more limited number of human mammary tumors and reacted with normal ductal epithelium in the breast and with nonbreast tissues. Because of their wide spectrum of reactivity with breast cancer cells and restricted recognition of normal mammary tissues, their cytoplasmic localization, and their heterogeneous distribution within a single neoplasm, 1F10B4 and 1F10G2 are now being used to characterize antigenic phenotypes of tumor-associated antigens in retrospective studies performed on conventional formalin-fixed, paraffin-embedded human mammary carcinomas.

The early nephrotoxicity of free and DNA-bound adriamycin (ADR) was compared in left nephrectomized rats. Free ADR induced progressive renal failure within 3 weeks, in association with renal changes characterized by severe tubular distention and vacuolization of podocytes in glomeruli. On the contrary, renal function remained normal and renal lesions were discrete in animals treated with ADR bound to DNA. Thus, the binding of ADR to DNA seems to reduce the early nephrotoxicity of free ADR.

Adriamycin (ADR) can be linked to DNA without loss of its antitumoral activity while reducing the acute toxicity of free ADR (Deprez--DeCampeneere et al., 1979, 1980). However, the potential chronic toxic effects of both forms of ADR are poorly documented. For such a study, it is necessary to establish the sequence of treatment allowing the administration of a sufficient amount of drugs to induce chronic toxicity and a schedule leading to prolonged survival of animals. In this study, 24 Lewis rats were injected twice a week during four weeks with either free or DNA-linked ADR, and three dose levels were tested: 4, 2 and 1 mg/kg. Our results indicated that the total cumulative dose of ADR should not exceed 8 mg/kg over one month, if prolonged survival is desired. The binding of ADR to DNA seemed also to reduce the acute toxic effects induced by free ADR, in rats. However, such a beneficial effect was not observed when the chronic nephrotoxicity was considered since characteristic renal lesions were observed in all long-term survivors, whatever the dose and the form of ADR received.

The chemotherapeutic effectiveness of the lysosomotropic Adriamycin-DNA complex has been demonstrated experimentally. This study evaluated the immunosuppressive activity of the complex on renal allografts in rats of the Buffalo-Lewis strain. Six rats receiving no treatment served as a control. Five rats received DNA along (at a dose equivalent to that in the complex), seven received the Adriamycin-DNA complex (molar ratio of DNA mononucleotide to Adriamycin, 20:1) and five were given free Adriamycin. Adriamycin, free or linked to DNA, was injected as follows: 2 mg/kg on days 2, 6 and 9 and 1 mg/kg on day 13 after transplantation. The Adriamycin-DNA complex prevented renal allograft rejection in the early postoperative period, by delaying for more than a week, the increase in serum creatinine levels in animals receiving transplants. Histologic examination of renal grafts in these rats confirmed the reduced severity of acute cellular rejection. There was also functional and morphologic evidence of reduced toxicity of Adriamycin when linked to DNA. The beneficial effect of such a drug should be attributed to its lysosomotropic mechanism of activity.

The glomerular fibrinolytic activity (GFA) was studied using the fibrin slides technique for isolated glomeruli in normal human cortex (N = 8) and in renal allografts (N = 11), in order to evaluate whether fibrinolysis is modified after rejection. In normal cases all glomeruli showed a lytic zone when incubated at 37°C during 150 min; the mean GFA value was 0.0313 ± 0.0021 min−1. A highly significant decrease of the number of glomeruli showing a lytic zone was noted in rejected renal allografts; however, in the glomeruli which retain their fibrinolytic capacity, the GFA did not increase. This study indicates that the GFA can be quantitatively estimated in human glomeruli and suggests that the normal fibrinolytic capacity of numerous glomeruli is lost in rejected renal allografts.