Gut-Derived Immune Effector Cells

Klein, John

Abstract

The intestinal mucosa constitutes a major host barrier to foreign antigen entry, yet current knowledge is fragmentary as to a) the types of specific immune effector cells which populate the gut-associated lymphoid tissues (GALT), and b) their functional role in immune protection. The goal of this research project is to study GALT immune effector cells with respect to function, phenotype and regulation, using fresh gut lymphocytes from normal and antigen-primed mice, and clonally-derived gut lymphocyte lines.
The first aim of this project is to characterize the types of cytotoxic effector cells present in the intestinal mucosa using fresh isolates of gut lymphocytes from normal and antigen-primed mice. These studies will use density gradients and FACS analyses to separate discrete cytotoxic effector populations. Isolated cytotoxic cells will be characterized as to target cell specificity using cold target competition studies, and as to their activation within the GALT following enteric infection with virus, bacteria, or parasites.
A second aim of this project is to establish long-term in vitro cloned cell lines derived from the GALT. These will include lines with cytotoxic and helper activities, and mucosal mast cells. Gut lymphocyte lines will be studied as to function, phenotype, and for their ability to elaborate lymphokines. Attempts will be made using gut lymphocyte clones to raise antisera specific for GALT lymphocyte antigens.
A third aim of this project is to characterize the activational and regulatory requirements governing GALT immune functions. These studies will examine factors which control gut cytotoxic responses in a specific manner following antigen priming, or nonspecifically using soluble mediators derived from lymphoid cells (T cells, mast cells). The influence of lymphokines on gut lymphocyte function will be studied using freshly isolated gut lymphocytes and long-term clones.
A fourth aim of this project is to study intestinal virus infection with respect to local immune mechanisms within the GALT. This includes studies which explore the potential for virus infection to initiate an autoimmune process mediated by cytotoxic cells within the GALT. In vitro and in vivo studies of autoreactivity have been designed. Collectively, the studies described here will address important questions pertaining to the functions and specificities of GALT immune cells and should help to expand our understanding of the mechanisms of disease and immunity within the intestinal tract.