Kemik iliği öncüllerinin ICAM-1 ekspresyonunda TSH aracılı IL-6 sekresyonunun önemi

Amaç: Bu çalışmada tiroid stimule edici hormonun (TSH) etkisi ile salgılanan IL-6'nın kemik iliği öncül hücrelerinin ICAM-1 ekspresyonu üzerindeki etkileri in vitro yöntemlerle araştırıldı. Ayrıca, stomal hücrelerin varlığının, öncüllerin ICAM-1 ekspresyonuna olan etkileri incelendi. Gereç ve Yöntem: Fare femur ve tibiasından elde edilen kemik iliği öncüllerinin, kültür ortamına TSH ilavesine cevap olarak IL-6 salgıladığı ELISA yöntemiyle araştırıldı. IL-6 ilave edilen kültürlerde kemik iliği öncüllerinin ICAM-1 ekspresyonu, akım sitometrik yöntemle belirlendi. Stromal hücrelerin bulunduğu kültür ortamında, lenfoid ve myeloid kökenli kemik iliği öncüllerinin ICAM-1 ekspresyonunu saptamak için de akım sitometrik yöntemler kullanıldı. Bulgular: TSH varlığında, kemik ilği hücrelerinin önemli miktarlarda IL-6'ın salgıladığı tespit edildi. IL-6'ın ICAM-1 ekspresyonunu kısmen baskılayıcı bir etki gösterdiği izlendi. Stromal hücrelerin varlığında ise hem lenfoid hemde myeloid kemik iliği öncül hücreleri üzerindeki ICAM-1 ekpresyonunda, önemli derecede artış gözlendi. Sonuç: Bu sonuçların ışığı altında, kemik iliği öncüllerinin IL-6 salgılamasında TSH'nın etkin olabildiği söylenebilir. Stromal hücrelerin varlığı, hem lenfoid hemde myeloid öncüllerin yüksek seviyelerde ICAM-1 eksprese edebilmeleri için önemli bir faktördür. IL-6'nın ICAM-1 ekpresyonunu baskılayıcı etkisi, stromal hücrelerin yokluğunda ortaya çıkmaktadır. Bu durumda, ICAM-1 ekpresyonunun artışından, stromal hücreler tarafından sagılanan diğer büyüme faktörlerinin sorumlu olabileceği fikri öne çıkmaktadır.

Significance TSH-mediated IL-6 secretion in expression of ICAM-1 on bone marrow precursors

Significance of TSH-Mediated IL-6 Secretion in Expression of ICAM-1 on Bone Marrow Precursors Aim: In this study effects of IL-6 secretion, which is mediated by thyroid stimulating hormon (TSH), on ICAM-1 expression of bone marrow procursors were investigated in an in vitro culture system. Additionally, ICAM-1 expression of bone marrow precursors was assessed in the presence of stromal cells. Materials and Methods: Bone marrow precursors which were isolated from tibia and femur were treated with TSH. IL-6 secretion induced by TSH treatment was quantified using ELISA. Expression of ICAM-1 on precursors which were stimulated with IL-6 was determined by flow cytometry. Lymphoid and myeloid precursors were cultured in the presence of stromal cells as a feeder layer. ICAM-1 expression was also determined by flow cytometry. Results: Precursors secreted IL-6 at significant levels following TSH treatment. IL-6 which was included in total bone marrow cultures in the absence of stromal cells suppressed ICAM-1 expression partially. However, lymphoid and myeloid precursors that were cultured in the presence of stromal cells expressed ICAM-1 at higher levels in comparison to precursors that were cultured in the absence of stromal cells. Conclusion: TSH is an efficient hormone to induce IL-6 secretion from bone marrow precursors. IL-6 suppresses ICAM-1 expression of bone marrow precursors if the cells are cultured in the absence of stromal cells. The presence of stromal cells in bone marrow cultures is a significant factor for both lenfoid and myeloid precursors to be able to express ICAM-1 at high levels. Therefore, other growth factors which are secreted by stromal cells may be responsible for the increased expression of ICAM-1.

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