ANALYSIS OF HUMAN COMMON BILE DUCT-ASSOCIATED T-CELLS - EVIDENCE FOR OLIGOCLONALITY, T-CELL CLONAL PERSISTENCE, AND EPITHELIAL-CELL RECOGNITION

The phenotype of T cells associated with the common bile duct (CBD) is unknown. We investigated the hypothesis that they behave like other i ntraepithelial lymphocytes (IEL). Thus, we sought to determine the phe notype, TCR repertoire, and epithelial recognition of T cells obtained during endoscopic retrograde cholangiopancreatography. Three subjects were studied: two with primary sclerosing cholangitis and one normal control. After establishing a short-term T cell line, cells were 1) st ained with mAbs for flow cytometric analysis, 2) analyzed for TCRB cha in transcript expression, and 3) used as effector cells for cytotoxici ty and proliferation. Flow cytometry revealed that for all the subject s 98% of the T cells were TCR-alpha beta-positive. Immunohistology of the CBD showed that the epithelium and lamina propria contained signif icant numbers of CD3(+)CD43(+)CD45RO(+) lymphocytes. Complementarity-d etermining region 3 length displays suggested that the CBD-derived lin es were oligoclonal. This was confirmed by cloning and random sequenci ng of PCR amplification products using TCRBV region family-specific pr imers; TCRB chain sequences were reiterated in all transcripts analyze d. In one case, two expanded TCRB clones could be identified that were persistent in the bile duct over a 1-yr period. The CBD-derived lines were cytolytic in a redirected lysis assay and caused cytolysis of an intestinal epithelial cell line (Caco-2). This recognition was likely preferential for intestinal epithelial cells, since a CBD-derived lin e exhibited proliferation to two intestinal epithelial cell lines (HT- 29 and Caco-2) but not three other lines (HepG2, human foreskin fibrob last, and KD). We conclude that the CBD contains IELs that share sever al characteristics with intestinal IELs.