CD1a is usually expressed by immature DCs (Arrighi et al, 2003
). Its expression by APC was recently supposed to be correlated to a better prognosis in breast cancers (Coventry and Morton, 2003b
; Poindexter et al, 2004
; Thomachot et al, 2004
). In particular, its overexpression by axillary lymph nodes could prevent lymph node metastases (Poindexter et al, 2004
); nevertheless, the authors of this work found a higher number of mature CD83-positive DCs, but not of immature CD1a-positive DCs, in tumour-free sentinel lymph nodes than those containing tumours. In addition, its expression by epithelial cells of in situ
ductal Ca of the breast was also suggested (Coventry and Heinzel, 2004
). Indeed, the density of CD1a+
DCs within human tumours has been already associated with longer survival.
Barrett's oesophagous is an acquired metaplastic condition that results by a phenotypic switch of undifferentiated epithelial elements present in oesophageal mucosa (Fahmy and King, 1993
; Chandrasoma et al, 2001
). Barrett's metaplasia of gastric type is characterised by the presence of columnar cells resembling the gastric foveolar ones (Zwas et al, 1986
). Although the presence of a severe inflammation was recently associated to a higher possibility to progress to cancer (Fitzgerald et al, 2002
), the lamina propria surrounding metaplastic epithelium shows commonly a mild inflammatory infiltrate (Lee, 1999
). Indeed, until now, the Dy arising on BM is the only well-established preneoplastic lesion of the oesophageal adenocarcinoma (Menke-Pluymers et al, 1993
; Clark et al, 1996
We already showed, in a smaller series, that CD1a may be expressed by epithelial cells of BM, both gastric and intestinal types (Cappello et al, 2003
). In particular, we postulated a diagnostic role of this marker and supposed that it may also be useful to predict prognosis. Moreover, we already hypothesised a proimmunitary role of CD1a expression by epithelial cells (La Rocca et al, 2004
), in accordance to Coventry and Heinzel (2004)
In the present work, we demonstrated that CD1a may have a diagnostic role for BM. In particular, the expression of CD1a by metaplastic epithelial cells might help to distinguish GTBM from the presence of ectopic gastric epithelium in the oesophageal mucosa, since gastric epithelium resulted negative. Moreover, our data strongly suggest a prognostic role of the expression of CD1a on GTBM; indeed, the number of FU-Dy and FU-Ca cases was significantly higher in the CD1a− GTBM group than in the CD1a+ GTBM group.
In our opinion, the present results may confirm that increased CD1a expression not only in DCs but above all in epithelial cells may prevent tumour progression, for instance regarding the evolution of GTBM towards Ca. The expression of CD1a on metaplastic epithelial cells might be induced by local humoral factors, like inflammatory cytokines, as well as other unknown stimulatory molecules.
In conclusion, our hypotheses concerning the diagnostic and prognostic role of CD1a for BM may be confirmed by the present work. Moreover, we suppose that CD1a expression may have an antitumoral role in BM mucosa, and also, as postulated, in neoplastic diseases arising at other anatomic sites (Coventry and Morton, 2003a
; Coventry and Heinzel, 2004
; Poindexter et al, 2004
). As a future objective, epithelial CD1a+ cells interaction with DCs or T cells remains to be further investigated. At this stage, the possible explanation for the role of CD1a ectopic expression by epithelial elements remains unclear.
Regarding the intercellular signalling strategies, we suppose that DCs induce tumour cells apoptosis following the production of certain extracellular cytokines, as already postulated (Joo et al, 2002
). It may be assumed that this is only one of the processes that take place following DCs activation. Considering the importance of intercellular signalling, mediated by both soluble factors and extracellular matrix-bound molecules, a future goal could be to determine the cytokine expression pattern of Barrett's metaplastic cells, and by what means it could modulate antitumour immune response. Indeed, although BM commonly shows a mild inflammatory infiltrate, we will consider now with great interest the investigation of the cellular features and molecular pattern of these immunitary cells.