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Airway hyperresponsiveness (AHR) is a hallmark of asthma and a heritable polygenic trait in the mouse. In the mouse, candidate gene products of hematopoietic origin implicated in asthma mapped to the regions of the previously defined quantitative trait loci. Since hematopoietic cells have been implicated in the pathogenesis of asthma, we evaluated the role of hematopoietic cells in general and T cells specifically in the genetic modulation of native airway responsiveness in mice. Here, with the use of bone marrow transplantation, anti-T-cell monoclonal antibody treatment and T-cell transfer, we demonstrate that intrinsic non-atopic AHR is mediated by T lymphocytes. Our data support the novel concept that, in the absence of identified environmental influences, T cells enhance genetically determined airway responsiveness.

Broad T cell depletion has been used as an integral part of treatment in transplantation and autoimmune diseases. Following depletion, residual T cells undergo homeostatic proliferation and convert to memory-like T cells. In this study, we investigated the effect of T cell depletion by antilymphocyte serum (ALS), a polyclonal anti-T cell Ab, on CD4+ regulatory T cells. After ALS treatment, CD4+CD25+ T cells underwent proliferation and expressed a memory T cell marker, CD44. One week after ALS treatment, both CD25+ and CD25− T cells exhibited increased suppression of alloresponses in vitro, which waned thereafter to the levels mediated by naive CD25+ and CD25− T cells. By real-time PCR analyses, ALS treatment of CD4-deficient mice adoptively transferred with Thy1.2+CD4+CD25+Foxp3+ and Thy1.1+CD4+CD25−Foxp3− T cells resulted in the appearance of Thy1.2+CD4+CD25−Foxp3+ and Thy1.1+CD4+CD25+Foxp3+ T cells, suggesting the conversion between CD25+ and CD25− T cells. Naive CD25+ T cells expressed a higher level of intracellular Bcl-xL than CD25− T cells. Up-regulation of the Bcl-xL molecule during ALS-induced homeostatic expansion further promoted survival of CD25+ and, to a lessor degree, CD25− cells. These results indicate that CD25+ T cells are spared from ALS-mediated deletion, with some CD25+ T cells converting to CD25− T cells, and continue to exhibit regulatory activity. The concomitant presence of T cell deletion and continuous regulatory T cell activity may underlie the therapeutic effect of ALS, particularly in treatment of autoimmune diseases.

Diabetic complications such as neuropathy, retinopathy, and renal and cardiovascular disease continue to pose major health risks for diabetic patients. Consequently, much effort has focused on approaches that could replace conventional insulin therapy and provide more precise regulation of blood glucose levels. The biohybrid perfused artificial pancreas was designed to incorporate islet tissue and a selectively permeable membrane that isolates this tissue from the immune system of the recipient. Biohybrid pancreas devices containing canine islet allografts were implanted in ten pancreatectomized dogs requiring 18 to 32 units of injected insulin daily. These implants resulted in good control of fasting glucose levels in six of these animals without further exogenous insulin for periods of up to 5 months.

We investigated the therapeutic effect of antilnphocyte serum (ALS) on clinically overt diabetes by using a nonobese diabetic (NOD) Immunotherapy with ALS. ALS was obtained by immunizing rabbits with a pool of lymph node cells prepared from NOD, C3H/He, DBA/2, and (C57BL/6 x A)F1 mice (11). A 0.4-ml injection of ALS was given intraperitoneally to diabetic NOD mice on days 0 (the first day of treatment regardless of the duration of diabetes) and +2. Control mice were given 0.4 ml ofnormal rabbit serum (NRS) on days 0 and +2. Blood glucose levels were monitored every 2-3 days initially and once a week thereafter. Achievement of euglycemia (<11 mM) and independence from exogenous insulin treatment after immunotherapy was defined as clinical remission.Immunotherapy with Monoclonal Antibodis (mAbs). Hybridoma cells producing anti-CD4 (anti-L3T4, clone GK 1.5) mAb were kindly provided by Kevin J. Lafferty (Barbara Davis Center for Juvenile Diabetes, Denver). Hybridomas producing anti-CD8 (anti-Lyt 2.1, clone 116-13.1, and antiLyt 2.2, clone 41-3.48) mAb were obtained from American Type Culture Collection. Ascites fluid that contained mAbs at -5 mg/ml was used. Diabetic NOD mice were treated with anti-CD4 mAb at 0.2 ml on days 0, 7, 14, and 21 and/or 0.1 ml of anti-CD8 (anti-Lyt 2.1) mAb on days 0 and 14. This treatment protocol has been shown (12) to achieve long-term removal of CD4' and/or CD8+ T lymphocytes from peripheral lymphoid organs in other inbred mouse strains. Control diabetic NOD mice were treated with 0.2 ml of anti-Lyt 2.2 mAb on days 0, 7, 14, and 21.Flow Cytometric Analysis. Peripheral lymph node cells were stained with fluorescein isothiocyanate conjugates of mAb 53-6.7 (anti-CD8) and phycoerythrin-conjugates of mAb GK1.5 (anti-CD4), both of which were obtained from Becton Dickinson. Two-color analysis was performed with a singlebeam flow cytometer, FACScan (Becton Dickinson) and the FACSCAN Research Software (Becton Dickinson).Islet Isolation and Transplantation. Because insulitis generally starts at 4 weeks of age (1), NOD islet donors were Abbreviations: NOD, nonobese diabetic; ALS, anti-lymphocyte serum; NRS, normal rabbit serum; mAb, monoclonal antibody.tTo whom reprint requests should be addressed at: CRI, New

FTY720, which does not cause generalized immunosuppression, may be a safe and benign therapeutic agent for chronic use to prevent or cure type 1 diabetes.