CD30-CD30 ligand interaction in primary cutaneous CD30(+) T-cell lymphomas: A clue to the pathophysiology of clinical regression

Primary CD30(+) cutaneous T-cell lymphomas (CTCLs) represent a spectrum of non-Hodgkin's lymphomas (NHLs) that have been well defined at the clinical, histologic, and immunologic level. This group, which includes 2 main entit ies (large cell lymphoma and lymphomatoid papulosis [LyP]) and borderline c ases, is characterized by the expression of CD30 antigen by neoplastic larg e cells at presentation, possible spontaneous regression of the skin lesion s, and generally favorable clinical course. Although the functional relevan ce of CD30 and its natural ligand (CD30L) expression in most cases of NHL i s presently undefined, previous studies indicate that CD30L is likely to me diate reduction of proliferation in CD30(+) anaplastic large-cell NHL, No i nformation is currently available concerning the expression of CD30L in pri mary CD30(+) CTCLs. In this study, we investigated the immunophenotypic and genotypic expression of CD30 and CD30L in different developmental phases o f skin lesions (growing v spontaneously regressing). By immunohistochemistr y, CD30L expression was detected in regressing lesions only; by molecular a nalysis, the expression of CD30L was clearly higher in regressing lesions t han in growing ones. CD30L, while expressed by some small lymphocytes, was most often coexpressed by CD30(+) neoplastic large cells, as demonstrated b y 2-color immunofluorescence and by immunohistochemistry on paraffin sectio ns. Taken together, these data suggest that CD30-CD30L interaction may play a role in the pathobiology of primary cutaneous CD30(+) lymphoproliferativ e disorders. In particular, CD30L (over)expression might have a major role in the mechanism of self-regression of skin lesions, the most distinctive c linical feature of this cutaneous lymphoma subtype. (C) 1999 by The America n Society of Hematology.