Expression of mouse embryonic epitope TEC-2 on human carcinoma-derived cell lines and characterization of its glycoprotein carriers.

Monoclonal antibody TEC-02, raised against mouse embryonal carcinoma cells, has been shown to react with murine preimplantation embryos and with a very limited number of adult mouse tissues. The target epitope, TEC-2, is a carbohydrate carried in mouse embryonal carcinoma cells by large glycoprotein-bound glycan. We report here the expression of TEC-2 epitope on human carcinoma-derived cell lines, HeLa and HS, and the properties of its carbohydrate carriers. Immunolabeling of Nonidet P-40 lysates of HeLa cells separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that TEC-2 antigens are polydispersed glycoconjugates of high molecular weight (mostly above 100,000). TEC-2 antigens detected by the two-site sandwich assay, in which the antigen is immobilized and detected with the same antibody, had a slightly higher molecular weight than those detected by the solid-phase assay. This suggests heterogeneity in the number of TEC-2 epitopes per carrier molecule. When the cells were lysed by Triton X-114 and the detergent and aqueous phases were separated by warming and centrifugation, most of the TEC-2 antigenic activity was found in the aqueous phase. TEC-2 antigens isolated by indirect precipitation from [3H]galactose-labeled HeLa cells were degraded by extensive pronase digestion or mild alkaline treatment to glycopeptides or oligosaccharides of low molecular weight. Thus, TEC-2 epitope in human HeLa cells is carried by carbohydrates of only several monosaccharide units. TEC-02 antibody was also found to bind to Tamm-Horsfall glycoprotein isolated from human urine and its binding was enhanced by desialylation. Combined data indicate that TEC-02 antibody recognizes the GalNAc beta 1----4Gal beta 1----4 structure which may be carried on different types of molecule, according to the site of their synthesis.

Activation of killer cells from blood of urinary bladder carcinoma patients by short-term treatment with recombinant interleukin 2.

Highly purified recombinant human interleukin 2 induced cytotoxicity of lymphocytes from urinary bladder carcinoma patients and from control healthy donors when added during an 18-h 51Cr microcytotoxicity assay against bladder carcinoma (T24) target cells. Similar levels of killer cell activation were detected in mononuclear cell preparations from bladder carcinoma patients and control healthy donors; hence, no defect in the responsiveness of bladder carcinoma patients' lymphocytes to interleukin 2 could be observed. The effect of the recombinant interleukin 2 was dose-dependent. Addition of monoclonal antibody 7E9 directed against cell-type restricted antigen associated with the T24 target cells and capable of inducing antibody-dependent cellular cytotoxicity could not increase the cytotoxicity-inducing effects of interleukin 2.

Immunotherapy of murine sarcomas with interleukin 2. I. Local administration of human recombinant IL-2 preparations.

The immunotherapeutic effect of human recombinant interleukin 2 was examined with a panel of MC-induced murine sarcomas carrying individual tumour-specific transplantation antigens. Repeated peritumoral injections of RIL-2 inhibited growth of five (MC11, MC13, MC14, MC15, MC16) out of six sarcomas in syngeneic mice. The sixth murine sarcoma (MC12) was resistant to the tumour-inhibitory effect of human recombinant IL-2 as well as to the tumour-inhibitory effect of murine and rat lymphoid IL-2 preparations. Since the IL-2-sensitive and IL-2-resistant sarcomas were induced with MC in mice of identical genotype and share most of their characteristics, they represent a useful model for investigation of structural target cell determinants and functional target cell properties responsible for the sensitivity of tumours to the immunotherapeutic effects of IL-2.

Immunotherapy of murine sarcomas with interleukin 2. II. Activation of killer cells by human recombinant IL-2.

Highly purified human recombinant interleukin 2 induced cytotoxicity in mouse spleen cells against mouse sarcoma cells when added during the 51Cr microcytotoxicity assay. It elicited similar levels of killer cell activation as did human lymphoid (Jurkat leukaemia-derived) or mouse lymphoid (EL-4 leukaemia-derived) IL-2 preparations. The susceptibility of six MC-induced mouse sarcomas to the cytolytic effect of lymphokine-activated killer cells was compared. Five (MC11, MC13, MC14, MC15, MC16) of six mouse sarcoma cell lines examined were sensitive in vitro to the LAK cell effect, whereas one cell line (MC12) was resistant. Since the sensitive and resistant target cell lines had been induced with the same carcinogen and in mice of the same genotype, they represent a very useful model for investigation of target cell structures responsible for the sensitivity to the LAK cell effect.

Tumour inhibitory effects of TCGF/IL-2/-containing preparations.

Supernatants from ConA-stimulated rat spleen cell cultures and from cultures of PMA-stimulated murine lymphoma subline EL-4TF were found to contain TCGF and to inhibit growth of a transplantable, MC-induced sarcoma MC11 in syngeneic mice. Tumour-inhibitory effects of the supernatants were dependent on local and repeated administration. Prior to use of the supernatants obtained from PMA-stimulated EL-4TF cell cultures, the dialysable PMA had to be removed; contamination with PMA was found to abolish the tumour-inhibitory effect of the supernatants and to produce enhancement of tumour growth. A significant tumour-inhibitory effect has also been obtained with partially purified TCGF prepared from culture supernatants of cloned EL-4TF cells by ammonium sulphate precipitation, ion-exchange (FPLC) chromatography, and AcA 44 Ultrogel filtration.