A model for preservation of thymocyte-depleted thymus

DiGeorge syndrome is a disorder caused by a microdeletion on the long arm of chromosome 22. Approximately 1% of patients diagnosed with DiGeorge syndrome may have an absence of a functional thymus, which characterizes the complete form of the syndrome. These patients require urgent treatment to reconstitute T cell immunity. Thymus transplantation is a promising investigational procedure for reconstitution of thymic function in infants with congenital athymia. Here, we demonstrate a possible optimization of the preparation of thymus slices for transplantation through prior depletion of thymocytes and leukocyte cell lineages followed by cryopreservation with cryoprotective media (5% dextran FP 40, 5% Me2SO, and 5% FBS) while preserving tissue architecture. Thymus fragments were stored in liquid nitrogen at -196°C for 30 days or one year. The tissue architecture of the fragments was preserved, including the distinction between medullary thymic epithelial cells (TECs), cortical TECs, and Hassall bodies. Moreover, depleted thymus fragments cryopreserved for one year were recolonized by intrathymic injections of 3×106 thymocytes per mL, demonstrating the capability of these fragments to support T cell development. Thus, this technique opens up the possibility of freezing and storing large volumes of thymus tissue for immediate transplantation into patients with DiGeorge syndrome or atypical (Omenn-like) phenotype

MOLECULAR TOXINOTYPING OF CLOSTRIDIUM PERFRINGENS AND CLOSTRIDIUM DIFFICILE CATTLE AND SWINE ISOLATES BY PCR ASSAYS

Clostridium perfringens and C. difficile are common causes of enteritis and enterotoxaemia in humans and domestic and wild animals. The purpose of this study was to investigate the enterotoxigenic profile of cattle and swine isolates by PCRs. Methods One hundred and nineteen bovine (faecal and intestine) samples and 110 swine faeces were analyzed by culture assay. All C. perfringens isolates were screened for the characterization of the toxinotype. C. difficile strains were PCR-tested for the presence of tcdA/tcdB and cdtA/cdtB genes. Results Overall, 53 bovine samples tested positive: 37 for C. perfringens and 16 for C. difficile. In two C. perfringens-positive diarrhoeic samples, C. difficile was also isolated. All C. perfringens isolates were type A; C. difficile strains resulted tcdA/tcdB and cdtA/cdtB-negative. Sixty-five swine resulted positive: 17 for C. perfringens and 38 for C. difficile. All C. perfringens isolates were type A; eight were also cpb2-positive. All C. difficile strains resulted tcdA/tcdB and cdtA/cdtB-negative. In one C. perfringens cpb2-positive diarrhoeic sample C. difficile (tcdA/tcdB and cdtA/cdtB-positive) was also isolated. Clinical Significance Understanding the diversity of toxigenic strains may lead to a greater understanding of the pathogenesis in cattle and swine and help in the development of effective intervention methods for controlling clostridial disease outbreaks