Expression of genes coding for the tumor necrosis factor and lymphotoxin ligand-receptor system in non-Hodgkin's lymphomas

Excessive production of the tumor necrosis factor (TNF) ligand-receptor sys tem has been found to contribute to the severity of non-Hodgkin's lymphoma (NHL). We therefore investigated the expression of TNF, lymphotoxin alpha ( LT alpha), lymphotoxin beta (LT beta), and their receptor (p55, p75, LT bet a -R) transcripts within the tumor tissue in different NHL histological sub types. The constitutive expression of genes coding for TNF-related ligands and receptors was found in almost all 31 NHL samples studied. Semi-quantita tive reverse transcription/polymerase chain reaction and computed densitome try assays revealed that the amounts of TNF: LT alpha, p55, and LT beta -R mRNA were higher in follicular NHL than in other histological entities. The refore tumor cell immunopurification was performed in representative follic ular NHL samples and consistent results were obtained. The pattern of LT be ta gene expression was different from that of the other molecules, indicati ng the existence of distinct mechanisms of gene regulation. These results i ndicate that the transcription of genes coding for the TNF ligand-receptor system in NHL tumor tissue is more widespread than originally thought and t hat the heterogeneity of their expressions might be related to histological features. The expression of TNF-related ligands and receptors in tumor tis sues is likely to contribute to the clinicopathological features of lymphoi d-derived malignancies.