Lymphokine mRNA Expression in the Human Intestinal Mucosa and PBL Determined by Quantitative RT/PCR

Abstract

Mucosal T-lymphocytes are unique in that they express predominantly phenotypic markers of activation such as IL-2R¹ and HML-1² and the “memory” cell phenotype CD45RO^3-5 but lack the lymph node homing receptor Leu-8.⁶ After challenge with specific Ag in vitro they do not proliferate but provide help for B-lymphocytes.⁷ Furthermore, after in vitro activation they express IL-2, IFNγ, IL-4 and IL-5⁸, lymphokines which are thought to be critical for host defense in the normal intestinal mucosa. Since relatively little is known about lymphokine production in the normal human intestine, we wanted to determine the in situ expression of these lymphokines. So far, most of the information has been obtained from in vitro studies of intestinal lymphocytes that were isolated from surgical specimens using enzymatic methods. In this study, colonoscopic biopsies from normal individuals were used as a source of intestinal lymphocytes. Since only a small amount of total cellular RNA was available for study, we developed a reverse transcription (RT)-PCR method to determine lymphokine mRNA that was both very sensitive and quantitative.