Mast cells express functional CD30 ligand and are the predominant CD30L-positive cells in Hodgkin's disease

Hodgkin's disease (HD) tumours are characterized by the presence of few tum our cells, the Hodgkin and Reed-Sternberg (FIRS) cells, surrounded by a lar ge amount of non-neoplastic cells. The role of this cell infiltrate for the development of HD is not known. CD30, belonging to the tumour necrosis fac tor receptor superfamily, is highly expressed on HRS cells and believed to be involved in tumourigenesis and tumour progression, Tumour samples from 4 2 patients were immunohistochemically double-stained for tryptase, a mast c ell-specific proteinase and CD30 ligand (CD30L). Tryptase-positive mast cel ls were present in ali tumours. Of these cells, 50% expressed CD30L and 66% of the CD30L-positive cells were mast cells. CD30L mRNA in in vitro develo ped normal mast cells and malignant human and murine mast cell lines was de tected using reverse transcription polymerase chain reaction. CD30L protein expressed on human mast cells was detected using flow cytometry. In a co-c ulture assay, the human mast cell line HMC-1 stimulated thymidine uptake in HRS cell lines, and the stimulation could be blocked using CD30L-specific monoclonal antibodies. In conclusion, mast cells are present in HD tumours and are the predominant CD30L-expressing cells. CD30L-CD30 interaction is a pathway by which mast cells may stimulate DNA synthesis in HRS cells.