The predicted models for the structures and mode of hormone binding of the glycoprotein hormone receptors are to a large extent consistent with currently available biochemical and mutational data. Repeated sequences in beta-barrel proteins are shown to have general implications for constraints on structure. Averaging techniques used here to recognize the structural motif in these receptors should also apply to other proteins with repeated sequences.

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BACKGROUND: Advanced multiple myeloma (MM) and Waldenströ m's macroglobulinemia (WM) are incurable B-cell malignancies. This is the first full clinical report of atacicept, a fusion protein that binds to and neutralises the B-cell survival factors, B-lymphocyte stimulator (BLyS) and A proliferation-inducing ligand (APRIL), in MM and WM. METHODS: In this open-label phase-I study, 16 patients with advanced disease (12 MM, 4 WM) received one cycle of five once-weekly subcutaneous injections of atacicept (2, 4, 7 or 10 mg kg À1 ). Patients with stable disease after cycle 1 entered an extension study (either two additional cycles (2, 4 and 7 mg kg À1 cohorts) or 15 consecutive weekly injections of atacicept 10 mg kg À1 ).

We have recently derived a series of cloned cell lines displaying natural killer (NK) cell-like activity from normal human fetal blood (25 weeks). The lines were obtained after repeated stimulation of mononuclear cells with allogeneic Epstein-Barr virus (EBV)-transformed B lymphocytes and are interleukin-2 (IL-2) dependent. Initial characterization of the clones has been reported previously. Certain of these clones have been found to have unusual surface characteristics, namely, they are recognized by several well-defined anti-T3 antibodies, but do not react with WT31, which is thought to recognise an invariant epitope of the human (Ti-alpha beta) structure. Transcription of the genes encoding the alpha- and beta-chains of the T-cell receptor was assessed in two of these clones (F6A4 and F6C7). Ti-beta genes were found to be expressed, whereas alpha messenger RNA was not detected in Northern blot analysis. These data strongly suggest that these cells do not produce a stoichiometric T3/Ti-alpha beta receptor complex. However, experiments performed with a monoclonal antibody (anti-NKFi) developed against F6C7 cells demonstrated the existence of a unique clonotypic structure [relative molecular mass (Mr) 85,000 (85K)] which is surface-associated with T3 proteins. Furthermore, both anti-T3 and anti-NKFi were found to block cytotoxic effector function. Together, the results support the view that T3 proteins are involved in non-major histocompatibility complex (MHC)-restricted cytotoxic reactions mediated by certain circulating fetal lymphocytes which are likely to use a clonotypic structure distinct from both the 'first' (alpha beta) and the putative 'second' (gamma delta) T-cell receptor to recognize their target. The present studies were designed to characterize this structure.

SummaryDisseminated intravascular coagulation (DIC) may lead to severe thrombotic or hemorrhagic complications. The present work was undertaken to study the effect of interleukin 6 (IL-6) on variations of key coagulation and fibrinolytic parameters in plasma in a baboon model of experimental DIC induced by injection of factor Xa and phospholipids at dosages leading to partial (48%) or complete fibrinogen depletion. Transient increases of D-dimer, fibrinopeptide A, thrombin-antithrombin and the activated partial thromboplastin time were observed. Each parameter had a particular (time and Xa/phospho- lipid dose dependent) pattern of changes. The principal effect of IL-6 was a more rapid restoration of fibrinogen concentrations and of overall coagulation tests. Injection of factor Xa/phospholipids led also to a rapid increase of tissue-type plasminogen activator (t-PA) the extent of which was dependent on Xa/phospholipid dose. Pretreatment with IL-6 induced a threefold increase of basal t-PA and a corresponding increase of the t-PA response. Plasminogen activator inhibitor type 1 (PAI-1) concentrations did not change after low dose Xa/phospholipids, but increased eightfold after high dose Xa/phospholipids. IL-6 pretreatment induced within 8 h a twentyfold increase of PAI-1 but no further increase was observed after injection of factor Xa/phospholipids.Thus, in vivo thrombin generation leads to dynamic modifications of the coagulation and fibrinolytic systems. The principal effect of IL-6 is a more rapid normalization of overall coagulation tests, due to normalization of fibrinogen, and an increased t-PA release response which is partially counteracted by increased PAI-1 concentrations.

Purpose: B-lymphocyte stimulator and a proliferation-inducing ligand regulate B-cell homeostasis and immunoglobulin production and are overexpressed in B-cell malignancies. Atacicept (TACI-Ig), a recombinant fusion protein that inhibits both B-lymphocyte stimulator and a proliferation-inducing ligand, may be a novel treatment for B-cell malignancies. Experimental Design: A phase 1, open-label, dose-escalation study of atacicept in patients with relapsed or refractory B-cell lymphoma was done. Atacicept was given s.c. weekly for 5 weeks to sequential patient cohorts at doses of 2, 4, 7, or 10 mg/kg. Patients responding or with stable disease were eligible for treatment on an extension study for up to 24 weeks or until disease progression. Results: All patients were heavily pretreated (median number of previous treatments, 5; range, 1-10), and four patients had previously received a stem cell transplant. Four patients were treated at the 2, 4, or 7 mg/kg dose levels, and three patients received 10 mg/kg of atacicept. Atacicept was well tolerated at all doses. Three adverse events with grade 3 severity were reported for one patient, including jaw pain, gastrointestinal hemorrhage, and sepsis; all were considered unrelated to atacicept. Pharmacokinetic results were nonlinear, and treatment with atacicept resulted in dose-dependent decreases in immunoglobulin concentrations. Two patients had stable disease at 8 weeks, entered the extension study, and received additional doses of atacicept with no safety or tolerability concerns. Conclusion: Atacicept at doses of up to 10 mg/kg was well tolerated and showed biological activity by decreasing immunoglobulin concentrations, although tumor responses were not observed.

The immune response to a vascularized allograft involves a complex series of events, including T cell activation. A critical marker of T cell activation is the acquisition of stereospecific membrane receptors for the lymphokine, interleukin 2 (IL-2) (1-4). While resting T cells lack IL-2 receptors, in vitro studies (5,6) indicate that essentially all lectin-or alloantigen-stimulated proliferating T cells express the IL-2 receptor. Moreover, the interaction of IL-2 with receptorbearing cells is required for the clonal expansion of activated T cells (1-13). Whereas engagement of the T cell receptor for antigen is the first step in T cell activation, the interaction of IL-2 with the newly expressed IL-2 receptor is a requisite step in the common pathway of activation of all T cells. The extension of these in vitro findings to the process of allograft rejection in vivo has not been extensively studied. IL-2 is necessary to reconstitute the acute rejection response in vivo in T cell-deprived rats (14). However, direct evidence in vivo that the IL-2 receptor is involved in allograft rejection has been lacking.The rat monoclonal antibody (mAb) M7/20 binds to the murine IL-2 receptor, as demonstrated by its capacity to bind activated but not resting T cells in flow cytometry experiments, to prevent IL-2-mediated DNA synthesis in an IL-2-dependent cytotoxic T lymphocyte cell line, to precipitate an N-glycosylated 58 kilodalton glycoprotein, and to competitively inhibit binding of radiolabelled IL-2 (15). As such, it offers an opportunity to direct immunosuppressive therapy selectively against IL-2 receptor-bearing cells during allograft rejection. In this report, we examine the effect of administration of M7/20 on survival of cardiac allografts in mice. Materials and MethodsAnimals. Inbred male mice, weighing 20-25 gm, of strains C57BL/10, B10.BR, and B10.AKM (The Jackson Laboratory, Bar Harbor, ME) were used throughout. These strains are completely mismatched for the H-2 locus, but share the same genetic background.Operative Technique. Vascularized, heterotopic heart allografts were performed as