Intestinal intraepithelial lymphocytes include precursors committed to the T cell receptor alpha beta lineage.

The majority of T cells develop in the thymus and exhibit well characterized phenotypic changes associated with their maturation. Previous analysis of intestinal intraepithelial lymphocytes (IEL) from nude mice and a variety of experimentally manipulated models led to the view that at least a portion of these cells represent a distinct T cell population that matures extrathymically. The IEL that are postulated to mature within the intestine include both T cell receptor (TCR) alpha beta- and gamma delta-bearing subpopulations. They can be distinguished from conventional thymically derived T cells in that they express an unusual coreceptor, a CD8alpha homodimer. In addition, they can utilize the Fc receptor gamma-chain in place of the CD3-associated zeta-chain for TCR signaling and their maturation depends on the interleukin 2 receptor beta-chain. Moreover, TCRalpha beta+CD8alpha alpha+ IEL are not subject to conventional thymic selection processes. To determine whether CD3(-)CD8alpha alpha+ IEL represent precursors of T cells developing extrathymically, we examined IEL from knockout mice lacking the recombination activating gene-1 (rag-1), CD3epsilon, or both Lck and Fyn, in which thymic T cell development is arrested. CD3(-)CD8alpha alpha+CD16(+) IEL from all three mutant strains, as well as from nude mice, included cells that express pre-TCRalpha transcripts, a marker of T cell commitment. These IEL from lck-/-fyn-/- animals exhibited TCR beta-gene rearrangement. However, CD3(-)CD8alpha alpha+CD16(+) IEL from epsilon-deficient mice had not undergone Dbeta-Jbeta joining, despite normal rearrangement at the TCRbeta locus in thymocytes from these animals. These results revealed another distinction between thymocytes and IEL, and suggested an unexpectedly early role for CD3epsilon in IEL maturation.

Characterisation of a panel of monoclonal antibodies raised against recombinant HCV core protein.

Hepatitis C virus (HCV) has as yet no practical culture system so any antigen or antibody studies must be carried out using recombinant antigens. In this study, HCV core sequence was amplified by PCR, inserted into pRSET, and expressed in E. coli. The resultant core protein was purified using nickel affinity chromatography which bound the six histidine tag attached to the N-terminus of the protein. After elution in imidazole buffer, the core protein was used to immunise Balb/c mice and monoclonal antibodies against HCV core were raised. Six monoclonals were examined in a variety of assays. All of them recognised the p27 kDa protein which they were raised against and 2D2 and 3D7 recognised the core component of an HCV Recombinant Immunoblot Assay (RIBA). None of the antibodies recognised the linear peptides in an Innolia HCV assay. 2D2 showed cytoplasmic granular staining in 1-5% of cells in frozen section of HCV infected livers. Cross-competition assays between themselves and human anti-HCV core positive sera divided the antibodies into two main groups (I and II), with a sub-division of group I into a and b. Group I antibodies were unable to be inhibited by human anti-HCV sera whereas group II antibodies were inhibited by these sera (up to 62%). Epitopes recognised by all the monoclonals were probably conformational with the group I epitope being located within the first 105 amino acids of the core sequence and the group II epitope between amino acids 105 and 160.

Detection of herpesvirus DNA in the large intestine of patients with ulcerative colitis and Crohn's disease using the nested polymerase chain reaction.

The prevalence of herpesvirus DNA was examined in inflammatory bowel disease tissue. DNA was extracted from resection and biopsy specimens of the large intestine from patients with ulcerative colitis (n = 21), patients with Crohn's disease (n = 29), and patients with noninflammatory bowel disease (controls) (n = 21). The nested polymerase chain reaction was used to detect viral DNA using primer pairs specific for either cytomegalovirus (CMV), herpes simplex virus 1 (HSV1), human herpesvirus 6 (HHV6), varicella zoster virus (VZV), or Epstein Barr virus (EBV). HSV1 and VZV DNA were not detected in any of tissue samples. There was a high prevalence of CMV (81%), HHV6 (76%), and EBV (76%) DNA in ulcerative colitis tissue compared to Crohn's disease tissues (CMV 66%, HHV6 45%, EBV 55%). Control tissue had a relatively low frequency of CMV (29%) and EBV (19%) DNA but a prevalence of HHV6 DNA similar to that of ulcerative colitis (86%). However, the simultaneous presence of HHV6 and CMV and/or EBV DNA in ulcerative colitis tissue (76%) was much greater than in either Crohn's disease tissues (38%) or control tissue (29%) (P < 0.05). There was a low prevalence of CMV, HHV6, and EBV DNA in peripheral blood mononuclear cells from all patient groups. CMV and EBV are capable of reactivating HHV6: the high prevalence of coexistent HHV6 infection with either or both of these two viruses in ulcerative colitis tissue suggests that they may play a synergistic role in the pathogenesis of this disease.