CONSTITUTIVE AND MODULATED CYTOKINE EXPRESSION IN 2 PERMANENT HUMAN BONE-MARROW STROMAL CELL-LINES

We present a detailed analysis of cytokine expression patterns of the two permanent human bone marrow stromal cell lines, L87/4 and L88/5. T hese cell lines, previously established in our laboratory, are highly radiotolerant without cell detachment and support long-term cultures o f CD34(+)-enriched human cord blood cells. RT-PCR analysis of 22 diffe rent cytokines or cytokine receptor mRNAs showed an almost identical e xpression pattern in the two stromal cell lines compared to primary hu man Dexter-type stroma. Since stromal feeder lines employed in long-te rm cultures usually are irradiated and grown in media containing corti costeroids, we analyzed the impact of irradiation and dexamethasone on cytokine production in the two cell lines by RT-PCR, Northern blot an alysis, bioassays, and RIAs. By RT-PCR analysis, constitutive mRNA exp ression of c-kit, G-CSF, GM-CSF, IL-1 beta, IL-6, IL-7, IL-8, IL-11, K it ligand (KL), LIF, M-CSF, MIP-1 alpha, TGF-beta, and TNF-alpha was d emonstrated in both cell lines, with L87/4 a more potent cytokine prod ucer than L88/5. Northern blot data showed an increase in mRNA levels for GM-CSF, IL-1 beta, and LIF by irradiation and IL-1 alpha treatment in both cell lines. IL-1 alpha-induced GM-CSF, IL-1 beta, IL-6, IL-11 , and LIF mRNA levels were reduced by the addition of dexamethasone, w hereas dexamethasone had no influence on the amounts of IL-1 alpha-ind uced G-CSF mRNA. L87/4 and, to a lower extent, L88/5 cells showed dexa methasone-dependent increases in KL mRNA, while KL mRNA levels were no t stimulated by IL-1 alpha.