Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) mediate the development of numerous inflammatory lung diseases. Since IL-1β is typically activated in situations where TNF-α is produced, it was hypothesized that IL-1β alters TNF-α-induced proinflammatory epithelial cell function by altering TNF receptor shedding and surface abundance. In this study, the impact of IL-1β on TNF-α-mediated chemokine production as well as TNF receptor surface expression and shedding were investigated from mouse pulmonary epithelial cells (MLE-15). Interleukin-1β rapidly and persistently enhanced soluble and surface TNFR2. These effects were dependent on TNFR1 expression. TNFR2 small-interfering RNA (siRNA) shifted IL-1β responses, significantly increasing surface and shed TNFR1 implying IL-1β selectively modifies TNF receptors depending on cellular receptor composition. mRNA expression of both receptors was unaltered by IL-1β up to 24 h or in combination with TNF-α indicating effects were post- transcriptional. Interleukin-1β pretreatment enhanced TNF-α-induced macrophage inflammatory protein (MIP)-2 and KC mRNA expression as well as MIP-2 and KC protein levels at the same time point analyzed. Experiments utilizing siRNA against the TNF receptors and a TNFR1 neutralizing antibody demonstrated TNF-α induced MIP-2 through TNFR1 whereas both receptors may have contributed to KC production. These data suggest IL-1β modulates TNF-α–mediated inflammatory lung diseases by enhancing epithelial cell TNF receptor surface expression.

Cryostat sections of normal human adult gastrointestinal mucosae were studied by double-label immunofluorescence with antibodies to CD3, CD4, CD8, CD5 and CD6, in parallel with antibodies fF1 and TCR61 against fl-chains and 6-chains of the T-cell receptor (TcR) types TcR2 (a/f) and TcRl (y/6), respectively. Virtually no TcRl + were found within the lamina propria. In the epithelial compartment, TcR1 + cells were infrequent: in the small bowel, -2% of T cells were TcR1 + . In the colonic epithelium, the percentage of T cells expressing y/6-chains was higher, with a mean value approximating 15-20%, although this apparently large percentage increase compared with small bowel reflects in part a much lower density ofcolonic IEL, as absolute numbers ofTCRbI + cells were comparable. Of the TcRl + population, about half were CD4-CD8-'double negatives' and the remainder were CD8+. TcRl + cells were also CD5-CD6-, irrespective of expression of CD8. No CD4+ cells expressing TcRl were observed: essentially all CD4+ cells were fF1+, with some variability of labelling intensity. Approximately 30-50% of the CD8+ subset expressed the PF1 antigen strongly. However, in the remaining TcRl -CD8+ cells, which were all of the CD5-CD6phenotype, expression of the flF1 antigen was only detectable when streptavidin and biotin conjugates were used for amplification of labelling. Thus, the CD8+ CD5subset, a prominent population of the epithelial compartment of the small bowel, was either TcR2dUII in the majority or TcRl + in a minority. Our data imply that y/6 TcRl cells may be actively excluded from intestinal lamina propria, and that any preferential localization that does occur is limited and is rather a feature of the colonic mucosa, rather than the small bowel.

The leucocyte adhesion molecules (beta 2 integrins) comprise CD11 alpha-chains and a common beta-chain (CD18). CD11a (leucocyte function-associated antigen 1, LFA-1) is expressed by most T cells, and is involved in antigen presentation by macrophages via its counter-receptor, intercellular adhesion molecule (ICAM-1, CD54). By criteria of double-label immunofluorescence of cryostat tissue sections, virtually all lamina propria T cells of the normal small bowel were found to express LFA-1 strongly. By contrast, only 30-60% of intra-epithelial lymphocytes (IEL) expressed detectable LFA-1, most of which were LFA-1 weak and CD18-. ICAM-1 was expressed strongly only by vascular endothelium. In coeliac disease, there was a modest increase of diffuse ICAM-1 expression in the lamina propria, mainly in the subepithelial zone, where ICAM-1+ macrophages were occasionally seen. There was also a slight overall increase in CD11a expression by IEL, seen predominantly in surface epithelium and mainly by the CD4+ minority subset, but not by CD4-CD8- (TcR gamma delta +) cells. These data suggest that the LFA-1/ICAM-1-dependent antigen presentation pathway is of minor importance to IEL in the normal small bowel, and does not assume a major role in coeliac disease.

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