PCR detection of cytokines in normal human and pagetic osteoblast‐like cells

We investigated the expression of cytokine transcripts in osteoblast‐like cells derived from explants of pagetic and normal bone. A reverse transcription‐linked PCR was used that allowed the simultaneous analysis of a range of cytokines. Normal osteoblast‐like cells were found to contain the transcripts for IL‐1β, IL‐6, and TGF‐β 1 . For the first time we detected in bone cells the two other mammalian isoforms of TGF‐β, β 2 , and β 3 . Furthermore, we have also identified mRNA for IL‐3 and the novel chemotactic factor, IL‐8. Using this sensitive technique it was not possible to detect mRNA for IL‐1α, IL‐2, IL‐4, IL‐5, IL‐7, TNF‐α, or interferon‐γ. The human osteosarcoma cell line Saos‐2 also showed a similar pattern of expression of these cytokines to primary osteoblast‐like cells, with the exception that TNF‐α was also identified. Cells isolated from pagetic bone showed essentially the same profile of cytokine expression as normal bone except that TNF‐α was also detected in two of four samples. The cytokine profile of successive populations of cells harvested from one explant culture at 9, 22, and 57 days showed a consistent pattern of cytokine expression, demonstrating the phenotypic stability of the osteoblast‐like cells in long‐term cultures.