Immunohistochemical Study of Lymphocytes Infiltrating the Pancreatic Islets of LETL Rats with Spontaneous Type I Diabetes

Abstract

We have examined the distribution of subpopulations of infiltrating lymphocytes in the pancreatic islets of diabetic LETL rats immunohistochemically by a method which uses monoclonal antibodies specific for rat lymphocytes.Cryostat sections of the pancreas from diabetic LETL rats aged 8 to 15 weeks were immunostained by the SAB method using MRC OX-34, W3/25, OX-8, OX-33, OX-39 and anti-asialo GM1, which recognize pan-T cells, T helper cells (Th) and some macrophages, T suppressor/cytotoxic cells (Tc/s), B cells, interleukin-2 receptors, and natural killer cells and some macrophages, respectively.Pancreatic islets from diabetic LETL rats showed islet destruction with severe insulitis. Most infiltrating mononuclear cells were found to be positive for OX-34 antigens. These T lymphocytes consisted of W3/25-positive cells and OX-8-positive cells. However, no interleukin 2 receptor expression on these lymphocytes or anti-asialo GM1 positive cells was observed. We conclude that T lymphocytes predominate among the infiltrating lymphocytes and that interleukin 2 receptor positive lymphocytes may disappear after the complete destruction of /3-cells in LETL rats.