We have developed a technique to isolate monocytes from human peripheral blood. The technique takes special care of completely eliminating platelets which are usually present in other preparations. Monocytes obtained in good yelds (2.5-5.0 x 105 cells/ml blood), were found to be 70-80% pure on the basis of morphological and histochemical criteria. Contamination was largely due to the presence of lymphocytes. Monocytes were incubated in the presence or absence of arachidonic acid and TXB2, PGE2 and 6-keto-PGF1α were measured by specific and sensitive radioimmunoassays. It was found that when cells were incubated for up to 1 hr, the production of PGs was low or absent even in the presence of 10 μM arachidonic acid in the incubation medium. However, when incubations were carried out for 24 hrs in the presence of at least 1% fetal calf serum a dramatic increase in TX-, production occurred, with levels as high as 150 ng x 10 cells. The ratio TXB2/PGE2 was around 3, while 6-keto-PGF was produced at a much lower level. In the same conditions, when care was taken to evaluate PGs already present in fetal serum and/or cross reactivity due to media generally employed, purified human lymphocytes appeared unable to produce detectable levels of the three PGs tested.
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