CYTOKINE GENE-EXPRESSION IN HUMAN MULTIPLE-MYELOMA

In the present study the gene expression of cytokines promoting in vit ro myeloma-cell growth was investigated by Northern blot analysis usin g total RNA of 36 tumour samples of patients with multiple myeloma (MM ) or plasma cell leukaemia and poly(A)+ RNA of 10 human myeloma cell l ines (HMCL). These cytokines included interleukin (IL)-1alpha, IL-1bet a, IL-3, IL-6, granulocyte-macrophage (GM)-colony-stimulating factor ( CSF) and granulocyte (G)-CSF. IL-1beta, IL-6 and G-CSF genes were coex pressed in most patients, although at variable levels. IL-1alpha trans cripts were detected in 32% of patients in whom coexpression of IL-1be ta gene was found. IL-3 gene was not expressed in patients' cells and GM-CSF mRNA was detected in only 1/32 patients. No detectable transcri pts for the above cytokines were present in HMCL, whereas IL-6 gene wa s expressed in 2/10 HMCL. We also looked for the presence of transcrip ts for IL-2, leukaemia inhibitory factor (LIF) and transforming growth factor (TGF)beta in cells of tumour samples from the same patients an d in HMCL. IL-2 gene was not expressed in MM patients and HMCL. Weak e xpression of LIF gene was detected in three patients (9%), and transfo rming growth factor beta (TGFbeta) mRNA was observed in 12/12 tumour s amples analysed and all HMCL. These results suggest that, among cytoki nes shown to control myeloma-cell growth in vitro, IL-1, IL-6 and G-CS F could play a role in the development of myeloma disease in vivo.