A new isolation method for rat intraepithelial lymphocytes

Intraepithelial lymphocytes (IELs) play critical roles in gut immunity. In mice, gamma delta T cells are a large component of the IEL population. In t he rat, gamma delta IELs are reportedly much less common, but technical iss ues suggest that previous analyses should be interpreted cautiously. The st udy of IELs in rats has been impeded by isolation procedures that are lengt hy and complex, leading to small cell yields. For this reason, it is possib le that rat IELs analyzed in previous studies have not been representative of the entire IEL compartment. We report a new method for the isolation of rat IELs that is based on the selective removal of intestinal epithelial ce lls under conditions that leave the basement membrane undisturbed. The meth od is rapid and requires neither enzymatic digestion, nor surgical removal of Peyer's patches, nor vigorous mechanical manipulation of the intestine. The yield of rat IELs using this method is 5- to 10-fold greater than that reported for other methods. Morphological and phenotypic analyses demonstra ted that the purified cell population is comprised of IELs and is not conta minated with lamina propria or Peyer's patch lymphocytes. Phenotypic analys is revealed five major subsets of IELs based on differential cell surface e xpression of CD4, CD8, and alpha beta T cell receptor (TcR). Among the alph a beta TcR- cells was a population of gamma delta T cells present at levels not previously detected. The isolation of IEL sub-populations using this m ethodology should facilitate studies of the function of these cells in gut immunity. (C) 1999 Elsevier Science B.V. All rights reserved.