T lineage-specific activation antigen 1 (TLiSA1) antigen was initially described as a T lineage-specific activation antigen involved in the differentiation of human cytotoxic T cells. Subsequently, the antigen was identified on platelets and was shown to be involved in platelet activation, hence it was renamed platelet and T cell antigen 1 (PTA1), although identity between the two antigens was not established. In the present study we have cloned the cDNA encoding TLiSA1 from Jurkat cells and show it to be a novel member of the immunoglobulin superfamily with the unusual structure of two V domains only. Identity between TLiSA1 and platelet PTA1 is established by immunological criteria, by internal peptide sequences obtained from the purified platelet glycoprotein and by sequencing the platelet transcript after reverse transcriptase-polymerase chain reaction. In Jurkat cells, TLiSA1/PTA1 mRNA and surface protein expression is greatly stimulated by treatment of the cells with phorbol ester, but the T cell proliferative signal of phorbol ester and ionophore combined greatly reduces or abrogates this response, and this suppressive effect of the ionophore is not reversed by incorporating FK506 to inhibit calcineurin. Together with the known signaling role of PTA1, these data substantiate the notion that this molecule is implicated in T cell differentiation, perhaps by engagement of an adhesive ligand.
Summary A mouse IgGi monoclonal antibody (1C4), which recognizes a cell surface molecule on murine natural cytotoxic{NC) cells was produced. By flowcytometry. IC4preferentially reacted with less than 5% of fresh CBA spleen cells and 20-50% of CBA-interleukin-3 (lL-3) cells, an in vitro derived NC-like cell line. In vitro treatment of spleen cells from a number of inbred mouse strains either with 1C4 alone or 1C4 coupled to dynabeads markedly decreased or abolished NC activity of the cells against ^'Cr-labelled WEHl-164 targets. Splenic NC activity of these same mouse strains was also reduced or abolished by in vivo administration of IC4. The effect was evident within 2 h of treatment and persisted for at least I week. In contrast IC4 had little or no effect on splenic NK activity against "Cr-labeiled YAC-I targets over the same range of experiments in vitro and in vivo. Results of strain surveys for both in vitro and in vivo reduction of splenic NC activity by 1C4 treatment showed that CBA. C57BL/6, BALB/c and NZB mice were positive and CE and DBA/2 mice were negative, indicating that 1C4 recognizes an allo-antigen on mouse NC cells. This allo-antibody has been designated NC-II, and thus IC4 is an anti-NC-11 monoclonal antibody.
SUMMARYWe have previously reported the identification by the murine monoclonal antibody (mAb) 1C4 of the first leucocyte receptor which is involved in natural cytotoxicity (NC ) against WEHI-164; the NC-1.1 receptor. We report herein the identification and characterization of a second leucocyte receptor which is involved in NC, NC-2 (MW 50 000), identified by a rat anti-mouse mAb D9 (immunoglobulin G2a; IgG2a). Flow cytometric analysis showed that NC-2 was expressed on<6% of splenic leucocytes of different inbred mouse strains and 96% of the cells of a mast-cell line which has high NC activity. In vitro treatment of splenic leucocytes with the D9 mAb blocked effector cell-WEHI-164 target cell conjugation and NC by # 50% without affecting natural killing (NK ). Western blot analysis of affinity purified NC-2 and NC-1.1 using the D9 and 1C4 mAbs showed specific reactivity of the proteins with D9 and 1C4, respectively. Pretreatment of splenic leucocytes with both mAbs blocked NC 84%, a result which almost doubled that caused by either mAb alone. Flow cytometric screening of 16 different mouse cell lines showed that 19% of the cell lines expressed both receptors, 6% expressed only NC-2, 44% expressed mainly or only NC-1.1 and the remaining cells expressed neither receptor. These data indicate that D9 identifies a xenoantigen, NC-2, which is expressed on cells mediating NC and not NK, and that it is not the previously described NC-1.1 allo-antigen. We conclude that NC-2 is likely to be one of a number of receptor molecules on cells mediating NC against tumour cells.
Blood from 1497 women who were either non‐pregnant, pregnant at all stages of gestation, lactating after parturition, postmenopausal, or who had benign breast lumps, primary breast cancer or advanced breast cancer were tested for their peripheral blood mammary serum antigen (MSA), using the 3E1.2 monoclonal antibody (MoAb) in an inhibition enzyme linked immunosorbent assay test system. The study aimed to establish normal ranges for comparison with MSA levels in breast cancer and benign breast disease. Compared with normal premenopausal women, which included women measured 8–10 times throughout their menstrual cycle, circulating MSA levels were significantly elevated throughout pregnancy (P > 0.0001), in postmenopausal women (P > 0.05), in women with primary breast cancer (P > 0.05) and women with advanced (metastatic) breast cancer (P > 0.0001). As a group, the 30 women with benign breast disease did not demonstrate significantly different MSA level from normal. However, 3% of the group did have levels above the cut off for normal (400 IU/mL). Analysis of the normal premenopausal women according to age, parity and stage of the menstrual cycle and during lactation showed that these parameters did not affect MSA levels. It is concluded that the test is potentially valuable in the detection of metastatic but not primary breast cancer, and the effects of pregnancy and postmenopausal status on the circulating MSA levels need to be considered in the interpretation of MSA measurements.
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