Tolerance induction in composite facial allograft transplantation in the rat model

Clinical application of composite tissue allograft transplants opened discussion on the restoration of facial deformities by allotransplantation. The authors introduce a hemifacial allograft transplant model to investigate the rationale for the development of functional tolerance across the major histocompatibility complex barrier. Eighteen rats in three groups were studied. The composite hemifacial allotransplantations including the ear and scalp were performed between Lewis-Brown Norway (RT1l+n) and Lewis (RT1l) rats and isotransplantations were performed between Lewis rats. Isograft controls (n = 6) and allograft controls (n = 6) did not receive treatment. Allografts in treatment group (n = 6) were treated with cyclosporine A 16 mg/kg/day during the first week; this dose was tapered to 2 mg/kg/day over 4 weeks and maintained at this level thereafter. Functional tolerance to face allografts was evaluated clinically and histologically. Donor-specific chimerism was assessed at days 21 and 63 by flow cytometry. In vitro evaluation of donor-specific tolerance was performed by mixed lymphocyte reaction at day 160 after transplantation. Isograft controls survived indefinitely. All nontreated allografts were rejected within 5 to 7 days after transplantation, as confirmed by histopathologic analysis. Five of six face allografts under the cyclosporine A protocol showed no signs of rejection for up to 240 days and remained alive and under evaluation, whereas one animal showed signs of rejection at day 140. This was reversed by adjustment of the cyclosporine A dose. At day 21 after transplantation, flow cytometric analysis of the donor-specific chimerism showed 1.11 percent of double-positive CD4FITC/RT1Ac-Cy7 and 1.43 percent of double-positive CD8PE/RT1Ac-Cy7 T-cell populations in the peripheral blood of hemiface allotransplant recipients. The chimerism level of double-positive CD4FITC/RT1Ac-Cy7 T cells increased to 3.39 percent, whereas it remained stable for the double-positive CD8PE/RT1Ac-Cy7 T-cell population at day 63 after transplantation (1.00 percent). The mixed lymphocyte reaction assay at day 160 after transplantation revealed donor-specific tolerance to donor (Lewis-Brown Norway) antigens and strong reactivity to the third-party (ACI) alloantigens. In this study, donor-specific chimerism and functional tolerance were induced in hemifacial allograft transplants across the major histocompatibility complex barrier under cyclosporine A monotherapy protocol. This model will allow further studies on tolerance induction protocols.     

PON1 55 and 192 Gene Polymorphisms in Type 2 Diabetes Mellitus Patients in a Turkish Population

Diabetes mellitus is a multifactorial metabolic disease, caused by the complete or relative absence of insulin hormone, which results in the deterioration of carbohydrate, protein, and lipid metabolism. The PON1 55 and 192 polymorphisms have been reported to be associated with type 2 diabetes and its complications. In this study, the involvement of the PON1 55 and 192 polymorphisms and paraoxonase enzyme activity in diabetic complications was assessed. The MM and QQ genotypes were the most frequent in complications of type 2 diabetes in both of the polymorphisms. PON enzyme activity was lower in the type 2 diabetes group with respect to the control group. Regarding both genotypes and enzyme activity, correlations were found between the PON1 55 and 192 genotypes and diabetic complications. This study thus helps to outline a genotype?Cphenotype relation for the PON1 gene in a Turkish population.     

Purification and biochemical characterization of a soluble mouse interferon-gamma receptor produced in insect cells.

The extracellular domain of the mouse interferon gamma receptor comprising amino acids 17-243 of the protein was produced in Spodoptera frugiperda cells infected with a recombinant baculovirus. The receptor was mainly secreted into the culture medium and was purified to homogeneity in several hundred milligram amounts. The purification procedure involved four chromatography steps and delivered a soluble and active receptor with an overall recovery of 30%. From each purification run, two pools of soluble receptor with the same interferon gamma binding capacity were isolated. Under reducing electrophoretic conditions the protein of pool I migrates as two bands of molecular masses 32 and 34 kDa and of pool II as two bands of 30 and 32 kDa. The soluble receptor of both pools carries a heterogeneous glycosylation. After deglycosylation it appears as one protein band of 27 kDa. N-linked carbohydrates contribute about 6 kDa and O-linked carbohydrates 1 kDa to its molecular mass. The nonreduced protein specifically binds interferon gamma on ligand blots and in a solid-phase binding system and competes for the binding of radiolabeled interferon gamma to the cell surface receptor. The soluble mouse interferon gamma receptor exists as a monomer in physiological buffer and binds interferon gamma in its dimeric form. It is stable at room temperature and against tryptic digestion, but is very sensitive to proteinase K digestion. The soluble mouse interferon gamma receptor produced in the insect/baculovirus expression system may prove useful to study the function of interferon gamma receptor as an antagonist of endogenous interferon gamma in the treatment of immunological and inflammatory disorders.