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In the present study we have analyzed superinduction of TNF-alpha mRNA and enhancement of TNF-alpha gene transcription by cycloheximide (Chx) in human blood monocytes isolated by continuous Percoll gradient and activated in vitro. In the same monocyte cultures, we have compared the rate of gene transcription of TNF-alpha, IL-1 beta, IL-8, and the P53-antioncogene under the influence of plastic adherence, Staphylococcus aureus Cowan 1 (SAC), and Chx added at different times of monocyte culture. It was shown that the cytokine genes have low or negligible transcriptional activity in freshly isolated monocytes, whereas P53 gene transcription was constant in freshly isolated and in vitro-stimulated cells. Transcription of the IL-1 beta and IL-8 genes was induced by adherence and was not more enhanced by SAC. Transcription of the TNF-alpha gene was not induced by adherence. Chx added at the beginning of the monocyte culture did not block TNF-alpha or IL-1 beta gene transcription. IL-8 gene transcription, however, was abrogated by Chx. Addition of SAC to monocyte culture containing Chx caused significant enhancement of TNF-alpha gene transcription. Addition of Chx after 2.5 or 4 h of SAC activation caused "superinduction" of TNF-alpha mRNA and enhancement of TNF-alpha gene transcription. The data imply that TNF-alpha gene transcription in activated human monocytes might be regulated by both positive and negative regulatory factors that differ in their stability and protein synthesis dependence. In addition, results demonstrate that TNF-alpha, IL-1 beta, IL-8, and p53 genes in human monocytes are differently regulated.

The p53 gene has been associated with malignant transformation as well as "anti-oncogene" activity. In the present report expression of p53 in resting and activated human blood monocytes and lymphocytes is analyzed. It is found that human monocytes freshly isolated by continuous percoll gradient centrifugation contained detectable level of p53 mRNA. Stimulation of monocytes by potent activation inducer Staphylococcus Aureus Cowan I for 3-5 hr caused disappearance of r53 mRNA. In contrast, induction of high level of TNF-alpha mRNA was detected. Addition of cycloheximide had no effect on p53 mRNA content in stimulated monocytes, and caused disappearance of mRNA in resting cells. In lymphocytes cultures p53 mRNA was absent in freshly isolated cells and in resting lymphocytes cultured for 20 hr. Activation of lymphocytes by lectin caused accumulation of p53 mRNA. We suggest that r53 gene regulation and functions might be different in human monocytes and lymphocytes.

The influence of human defensin HNP-1 on the synthesis of tumor necrosis factor-alpha (TNF-alpha) by human blood monocytes was studied. It was shown that TNF-alpha production by human monocytes activated by SAC or PMA was augmented in the presence of HNP-1 concentrations of 10(-8)-10(-9) M. HNP-1 alone induced no synthesis of TNF-alpha. High concentration of HNP-1 (10(-4) M) was cytotoxic for human monocytes.