Leukotriene B5 (LTB5) that is generated enzymatically from eicosapentaenoic acid (EPA), was compared with arachidonic acid-derived LTB4 for its DNA synthetic effect on cultured human epidermal keratinocytes and for its chemokinetic effect on human blood neutrophils. Leukotriene B5 was much less potent than LTB4 in stimulating DNA synthesis and in inducing chemokinesis. Furthermore, the maximum response to LTB5 was only a mean of 38% that of LTB4 for mitogenesis and 70% that of LTB4 for chemokinesis. At an optimally active concentration of LTB4 (10(-10) M) the addition of LTB5 suppressed the enhancement by LTB4 of DNA synthesis in keratinocytes by a mean of 21%, 33%, and 54%, respectively, at 10(-9) M, 10(-8) M, and 10(-7) M LTB5. Inhibition by Leukotriene B5 of Leukotriene B4-Induced Activation of Human Keratinocytes and Neutrophils.
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