Histological and cellular analysis of isolated lymphoid follicles in terminal ileum of long term intestinal transplant recipients, initial report

DOMINIK MEIER; HERNÁN CAGNOLA; FERNANDO CHIRDO; GUILLERMO DOCENA; RAMISCH DIEGO; GABRIEL GONDOLES; MARTIN RUMBO

Bologna, Italy

Congreso; XI International Small Bowel Transplant Symposium.; 2009

International Society of Intestinal Transplantation

Introduction: Isolated Lymphoid Follicles (ILF) are small lymphoid structures, located throughout the small intestine, that contribute to gut immune responses. The impact of immunosuppressive therapy applied upon intestinal transplantation (ITx) on ILF structure is unknown. We addressed the questions whether number, structure, and cellular contents of ILF is conserved upon ITx.   Methods: Surgical samples from distal ileum of 5 patients that underwent ileostomy closure operation 15+/-8 months after transplant ITx were studied. 4 patients from non-ITx operation were included as controls. Surgery specimens were dissected in layers for identification of ILF. Cellular composition of ILF was characterized by immunohistochemistry and flow cytometry.   Results: We could not detect differences in frequency of ILF presence between ITx patients and normal intestine. A similar density of ILF (around 15 to 20 ILF per cm2 in all cases evaluated) and total cell counts (around one hundred thousand mononuclear cells per ILF) were observed. ILF were constituted mainly of CD19+CD20+ B cells, fewer CD4+ and CD8+ T cells, and some CD11c+ cells. Nevertheless, flow cytometry analysis showed lower percentage of CD19+ B (30 vs 50%) cells and increase in CD3+CD8+ T (15 to 30%) cells in ILF from ITx when compared with non-ITx patients.   Conclusions: In spite of immunosuppression, ILF are still present in the ileal mucosa several months after ITx. However, changes in the B/T cell ratio of ILF after ITx were detected. The analysis of samples from ileostomy closure operation might be useful to improve our understanding in intestinal immunobiology upon ITx.