engleski

CD10 and CD13 expression on cultured human keratinocytes

Membrane aminopeptidases expressed on cells of hematopoietic origin are involved in specific immune response (antigen processing and presentation) and in inflammation (cleavage of some cytokines and chemokines). Keratinocytes, epidermal skin cells, also secrete cytokines and participate in skin immune response. Aminopeptidases expressed on keratinocytes, like those on lymphocytes and granulocytes, might regulate local cytokine concentration. Therefore, we examined the expression of two main membrane aminopeptidases involved in cytokine and neuropeptide cleavage, aminopeptidase N (APN ; EC 3.4.11.2 ; CD13) and neutral aminopeptidase (NEP ; EC 3.4.24.11 ; CD10). This was done on primary cultures of human keratinocytes at the level of membrane expression (immunohistochemistry) and mRNA (RT-PCR). Cultured human skin fibroblasts (CD10+/CD13+) and human cell lines NALM-6 (CD10+) and HL-60 (CD13+ ) served as positive controls Keratinocytes were obtained from skin of burned patients and were cultured in serum-free medium, with supplements for their selective growth (DKSFM). Purity of cultured populations was checked by anti-cytokeratin antibodies and was above 90%. Only scarce mRNA for CD10 and CD13 was observed in 2 out of 4 samples, and 2 samples were negative. In contrast, mRNA for CD10 was highly expressed on human fibroblasts and cells of the NALM-6 line, and mRNA for CD13 cells was highly expressed on human fibroblasts and cells of the HL-60 line. Thus, the observed low level of mRNA for CD10 and CD13 found on two samples of cultured keratinocytes might either be due to (a) low expression of these aminopeptidases on keratinocytes or (b) to contaminating fibroblasts. Analysis of membrane expression of CD10 and CD13 on samples of cultured keratinocytes will help distinguish these possibilities. Activation of cultured keratinocytes by inflammatory/anti-inflamatory cytokines might up-regulate expression of these aminopeptidases and help their identification.

keratinocytes; aminopeptidase N; neutral endopeptidase

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