No abstract

The L&H cells of nodular lymphocyte-predominant Hodgkin's disease represent a monoclonal expansion of B cells. The high load of V(H) gene mutations and signs of intraclonal diversity suggest a relation between L&H cells and germinal-center B cells at the centroblastic stage of differentiation.

Background-Clonal T cell receptor (TCR) gene rearrangements and loss of T cell antigens such as CD8 and TCR-in intraepithelial lymphocytes (IELs) may indicate the development of an enteropathy-type intestinal T cell lymphoma (EITCL) in patients with refractory sprue. Aims-To define the diagnostic value of these markers in duodenal biopsies from patients with villous atrophy as a result of various underlying disorders. Patients and methods-Duodenal biopsies from eight patients with coeliac disease and five patients with villous atrophy caused by defined disorders were compared with three patients with refractory sprue evolving into overt EITCL, two patients with ulcerative jejunitis, and with eight patients with overt EITCL, for expression of CD3, CD4, CD8, and TCRin IELs using immunohistochemistry and for clonal TCR-gene rearrangements using polymerase chain reaction. In addition, biopsies from six consecutive patients with refractory sprue of uncertain cause were examined. Results-Clonal TCR-gene rearrangements were found in all resected tumours of patients with EITCL, in 3/8 duodenal biopsies of patients with EITCL, in 2/2 patients with ulcerative jejunitis, in 2/3 patients with refractory sprue evolving into overt EITCL, and in 1/6 patients with refractory sprue. No rearrangements were found in biopsies from patients with refractory sprue caused by defined disorders or those with coeliac disease. Clonality in duodenal biopsies was associated with an abnormal phenotype of IELs in all cases and in all but one case in patients with evidence of underlying coeliac disease. Specificity for detection of an EITCL using immunohistology was 77% for CD8 and for TCR-staining, and 100% for detection of a clonal TCR-gene rearrangement. Sensitivity was 62% for staining with CD8 and clonality investigation, while sensitivity reached 100% for TCRstaining in all investigated patients with EITCL. Conclusions-Clonal proliferations of phenotypically abnormal IELs in refractory sprue represent an early manifestation of EITCL, for which the term "spruelike intestinal T cell lymphoma" is proposed. This constellation is also found in duodenal biopsies from patients with an overt EITCL and is not related to other sprue syndromes, resulting in a high specificity for detection of an EITCL or refractory sprue evolving into EITCL. Overt EITCL may develop directly from coeliac disease without a precursor lesion (refractory sprue with clonal IELs) being demonstrable in duodenal biopsies or via a "sprue-like intestinal T cell lymphoma". This latter entity is a complication of coeliac disease. (Gut 2001;49:804-812)

The decreased ratio of collagen I and TIMP-1 mRNA expressing cells to MMP-1 and MMP-3 mRNA expressing cells in untreated CD suggests a shift towards ECM degradation. ECM degradation by activated subepithelial fibroblasts and macrophages may be an important mechanism driving mucosal transformation in CD.

To further specify the cellular origin and nature of anaplastic large- cell lymphoma (ALCL) and its relationship to other lymphoid neoplasms, particularly Hodgkin's disease (HD), we investigated the presence of cytotoxic molecules in a large well-characterized series of these tumors. For expression of the cytotoxic molecules perforin and granzyme B, in situ hybridization (ISH) and immunohistology were used, respectively. Overall, 23 of 25 ALCLs of T/null phenotype and five (three mixed cellularity and two nodular sclerosis) of 57 HD cases showed the presence of perforin transcripts and/or granzyme B molecules in neoplastic cells. Polymerase chain reaction (PCR) analysis of ALCLs showed that most (10 of 11) cases of null-cell ALCL (null-ALCL) contained a clonal rearrangement of T-cell receptor beta-chain genes, as did T-cell ALCL (T-ALCL; 9 of 10 cases). However, both cytotoxic molecules and clonally rearranged T-cell receptor beta-chain genes were absent in seven of seven and eight of nine cases of B-cell ALCL (B-ALCL), respectively. These data show that all or nearly all T-ALCLs, irrespective of the clinical subform or the lack of T-cell-associated molecules, are derived from activated cytotoxic T cells. The same appears to be true for the neoplastic cells of rare HD cases. These findings indicate that T-ALCLs are different from B-ALCLs and the majority of HD cases, and suggest that some HD cases, especially those with T-cell antigen-positive tumor cells, may be closely related to T- ALCL, at least in terms of cellular origin.