Circulating neutrophils were investigated in 15 patients with Crohn's disease (CD), 15 with ulcerative colitis (UC), and 15 healthy volunteers. Dose-response curves for chemotaxis in Boyden chambers were analysed for sensitivity to leukotriene B4 (LTB4), its 20-hydroxy-LTB4 (20-OH-LTB4) and 20-carboxy-LTB4 (20-COOH-LTB4) catabolites, and 5- and 15-hydroxyeicosatetraenoic acids (HETEs). Positive controls included: complement 5a (C5a), formy-L-methionyl-L-leucyl-L-phenylalanine (f-Met-Leu-Phe), and casein. Control chemotaxis test were performed at concentrations yielding optimal responses in leucocytes of healthy volunteers. Chemotaxis to suboptimal concentrations of LTB4 1.0 and 3.2 nmol/l, and 5-HETE 316 nmol/l, was markedly depressed in patients with chronic inflammatory bowel disease (CIBD). Analyses of individual dose-response curves revealed an underlying decreased sensitivity to LTB4 in 11 out of 30 patients, to 5-HETE in 10 out of 30 patients with a corresponding decrease of median sensitivity to LTB4 and 5-HETE in both CD and UC. Peak responses to LTB4, 5-HETE, f-Met-Leu-Phe, and casein were identical in the three groups tested, whereas the C5a values were significantly depressed in both groups of patients (p less than 0.05). The potency of LTB4 exceeded that of 5-HETE by a factor of approximately 100 whereas 20-OH-LTB4 was nearly as potent as LTB4. 20-COOH-LTB4 and 15-HETE did not activate chemotaxis of human neutrophils. These findings are suggestive of a competitive inhibition of receptors with heterogeneity for LTB4 and 5-HETE.(ABSTRACT TRUNCATED AT 250 WORDS)