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In this study, we have investigated the effect of hydrophobic and hydrophilic unconjugated bile acids (UBAs)—ursodeoxycholic acid (UDCA), chenodeoxycholic acid (CDCA), lithocholic acid, and colic acid—on chemotaxis in adult and neonatal human polymorphonuclear leukocytes (PMNs). The trypan blue exclusion dye test was preliminarily performed to determine the toxicity of the studied UBAs on PMNs. N-formyl-methionyl-leucyl-phenylalanine (100 nM) was used as a chemoattractant. Chemotaxis (1 × 106cells/mL) was analyzed in the presence or absence of UBAs (10 M) by blind well chambers. The antioxidants vitamin E and vitamin C were tested for their ability to reduce the inhibitory effect of UBAs. We found that only CDCA was able to induce damage in PMNs in the range of 1–40 M. Both CDCA and UDCA were able to inhibit chemotaxis in PMNs, whereas lithocholic acid and colic acid were ineffective. The inhibitory effect was reversible inasmuch as PMNs incubated with either CDCA or UDCA and subsequently washed showed normal chemotaxis. Concomitant incubation of PMNs with UBAs and vitamins C or E reversed the inhibition. We did not find substantial differences between PMNs from adults or newborns. In conclusion, CDCA and UDCA are able to reduce, in a specific and reversible fashion, both adult and newborn neutrophil chemotaxis. As concomitant incubation of UBAs and electron scavengers restores PMN chemotaxis to control values, we conclude that free radicals may be involved in the mechanism of inhibition. We speculate that this defect may contribute to the impaired host response described in cholestatic patient.

ABSTRACT: Leukotriene B4(LTB4) is a potent mediator of inflammation generated by polymorphonuclear leukocytes (PMN) in response to an appropriate stimulus. It acts as a chemoat-tractant and stimulates PMN functions, amplifying their inflammatory response. Newborn infants show an increased susceptibility to infections in which PMN dysfunctions play the main role. In this work, LTB4release from neonatal polymorphonuclear cells was assessed to investigate whether a defect was detectable. Blood was obtained from the umbilical cord of 10 full-term healthy neonates and 10 adult controls. The LTB4production from purified PMN suspensions was induced by three different stimuli: the calcium ionophore A23187, serum-treated zymosan, and formyl-methionyl-leucyl-phenylalanine at final concentrations of 2 µM, 10 mg/mL, and 10 µM, respectively. The kinetics of LTB4release were studied for up to 30 min by assaying the supernatants of the stimulated cells with a specific RIA. The LTB4release, undetectable in resting PMN, was strongly stimulated by the A23187, peaking at 5 min, with significantly higher levels (t test, p < 0.01) in newborn than in adult PMN preparations (means ± SD: 12.46 ± 2.96 and 6.21 ± 2.09 ng/106cells, respectively). In comparison, serum-treated zymosan-stimulated PMN released smaller amounts of LTB4. The levels peaked at 10 min and were significantly (t test, p < 0.01) lower in newborn than in adult samples (means ± SD: 0.71 ± 0.22 and 3.19 ± 1.06 ng/106PMN, respectively). Finally, when the PMN were stimulated by formyl-methionyl-leucyl-phenylalanine, the release of LTB4was highly variable both in newborn and in adult samples, as previously reported. In conclusion, the PMN response to A23187 provides evidence that in neonatal PMN the lipoxygenase pathway for LTB4synthesis is already fully developed at birth. However, the neonatal cells were defective when triggered by a receptor-mediated stimulus, suggesting the presence of a limiting step in transmem-brane signal transduction that results in a low response in neonatal PMN.

Evidence is accumulating which indicates that immune reactions to gliadins are involved in the pathogenesis of celiac disease, as humoral- and cell-mediated immune responses to gliadins have been demonstrated in the jejunal mucosa and the peripheral blood of patients. An abnormal specific immunological response to gliadins is demonstrated not only in celiac children but also in their first-degree relatives. Seventy-eight percent of celiac patients, and 67, 87, and 100 of their fathers, siblings, and mothers, respectively, have a peripheral blood lymphocyte population reacting in vitrowith a proliferation response to at least one of four peptide mixtures obtained from bread and durum wheat gliadins using a procedure simulating in vivoprotein digestion. The specificity of this immunological hyperresponsiveness against wheat gliadins is shown by two sets of data: (a) Lymphocytes from celiac children and their relatives were much less sensitive to peptides from rice prolamin and not at all sensitive to peptides from wheat albumins. (b) Only 7 of 30 adult controls had a proliferative response of their peripheral lymphocytes to wheat gliadin peptides. It is not known at this time if healthy relatives of celiac patients mount an immune response against the intestine in vivo. However, it is possible that the presence of lymphocytes reactive to wheat gliadin peptides in apparently healthy relatives of celiac patients may explain why these relatives develop histologic evidence of celiac disease when their gluten intake is increased (Doherty M. Barry RF. Lancet1981:1:517–20).

Evidence is accumulating which indicates that immune reactions to gliadins are involved in the pathogenesis of celiac disease, as humoral- and cell-mediated immune responses to gliadins have been demonstrated in the jejunal mucosa and the peripheral blood of patients. An abnormal specific immunological response to gliadins is demonstrated not only in celiac children but also in their first-degree relatives. Seventy-eight percent of celiac patients, and 67, 87, and 100% of their fathers, siblings, and mothers, respectively, have a peripheral blood lymphocyte population reacting in vitrowith a proliferation response to at least one of four peptide mixtures obtained from bread and durum wheat gliadins using a procedure simulating in vivoprotein digestion. The specificity of this immunological hyperresponsiveness against wheat gliadins is shown by two sets of data: (a) Lymphocytes from celiac children and their relatives were much less sensitive to peptides from rice prolamin and not at all sensitive to peptides from wheat albumins. (b) Only 7% of 30 adult controls had a proliferative response of their peripheral lymphocytes to wheat gliadin peptides. It is not known at this time if healthy relatives of celiac patients mount an immune response against the intestine in vivo. However, it is possible that the presence of lymphocytes reactive to wheat gliadin peptides in apparently healthy relatives of celiac patients may explain why these relatives develop histologic evidence of celiac disease when their gluten intake is increased (Doherty M. Barry RF. Lancet1981:1:517–20).

The effect of short-term immunosuppressive treatment on the percentage of circulating DR-bearing T cells was investigated in 16 children with HBsAg-positive chronic active hepatitis. DR-positive T cells, thought to represent activated T cells, were significantly increased in all patients as compared to 10 age-matched controls [14.5 ± 4.2 (mean ± SD) vs. 0.4 ± 0.1, p< 0.001]. Fifty-six percent of patients showed a decrease in the percentage of DR-positive T cells after 72 h of prednisone therapy. A response did not correlate with the presence of HBeAg, anti-HBeAg, or anti-delta antibodies. There was an inverse relationship (r= -0.56; p< 0.05) between the decrease of the percent of DR-positive T cells during immunosuppression and pretreatment alanine aminotransferase levels. The persistence of high levels of circulating DR-bearing T cells during therapy may represent the immunological counterpart of more severe disease, and of nonresponsiveness to corticosteroids.