Luminol-dependent Chemiluminescence Response Research Articles

Mechanisms Involved in the Augmentation of Arachidonic Acid-Induced Free-Radical Generation from Rat Neutrophils following Hypoxia–Reoxygenation

Polymorphonuclear leukocytes are known to play an important role in hypoxia/ischemia and reoxygenation injury. The present study was undertaken to investigate the involvement of protein kinase C, calmodulin, and cyclic adenosine monophosphate in the augmentation of the free-radical generation observed after hypoxia–reoxygenation (H–R). Free-radical generation from the rat polymorphonuclear leukocytes was measured as the arachidonic acid (1–5×10 −5 M)-induced luminol-dependent chemiluminescence response, which was augmented following H–R. The increase in free-radical generation after H–R was completely blocked by the pretreatment of cells with PKC inhibitor H 7, whereas indomethacin (a cyclo-oxygenase inhibitor) or forskolin (an adenylate cyclase activator) failed to modulate the H–R-dependent response. However, W 7—a calcium/calmodulin (Ca 2+/CaM) antagonist—partially reduced the augmented free-radical generation observed in the H–R cells. Results obtained thus suggest the possible involvement of protein kinase C and calcium in the augmentation of the free-radical generation response following H–R.

Applicability of chemiluminescence to assess the degree of operative stress in patients undergoing spinal surgery.

This study examined the applicability of luminol-dependent chemiluminescence (CL) response of neutrophils to assess the degree of stress of spinal surgery by measuring the capacity of circulating neutrophils to produce reactive oxygen species and the levels of serum cytokines: interleukin(IL)-1beta, IL-6, IL-8, tumour necrosis factor (TNF)-alpha and granulocyte colony stimulating factor (G-CSF). Ten male patients underwent spinal surgery. Peripheral blood samples, collected before and after the operation and the next morning, were used for measuring the CL response of neutrophils stimulated with opsonized zymosan and measuring the levels of serum cytokines. The operative stress induced leukocytosis, particularly granulocytosis, and increased serum IL-6 and G-CSF significantly. However, there was no significant change in the luminol-dependent CL response of neutrophils or the levels of serum IL-1beta, IL-8 and TNF-alpha throughout the experimental period. These results suggest that, at least in the early postoperative period, operative stress does not prime the circulating neutrophils, and thus the CL response of neutrophils is not appropriate to assess the degree of stress of spinal surgery.

The effect of erdosteine and its active metabolite on reactive oxygen species production by inflammatory cells.

We examined the effect of erdosteine (KW-9144), an expectorant, and related compounds on inflammatory cell-derived reactive oxygen species which are involved in airway inflammation. Neutrophils were isolated from peritoneal lavages of casein-injected rats and from peripheral blood of healthy human donors. Eosinophils were isolated from peritoneal lavages of horse serum-injected guinea pigs. These cells were stimulated with phorbol 12-myristate 13-acetate (PMA) and the production of reactive oxygen species was measured with luminol-dependent chemiluminescence (LDCL). M1, an active metabolite of erdosteine, significantly inhibited PMA-induced LDCL of the all cell populations with treatment before stimulation. The effects of S-carboxymethylcysteine (S-CMC), ambroxol and N-acetylcysteine (NAC) on the LDCL response were weaker than those of M1. Furthermore, PMA-induced LDCL was decreased by posttreatment with M1. These results suggest that M (an active metabolite of erdosteine) may exert an antiinflammatory effect by scavenging inflammatory cells-derived reactive oxygen species.

EFFECTS OF MAXIMAL EXERCISE ON NONSPECIFIC IMMUNITY IN ATHLETES UNDER TRAINED AND DETRAINED CONDITIONS

We investigated both the acute effects of maximal exercise and the chronic effects of training on nonspecific immunity in 15 winter-sports athletes during different periods of training : (a) before the athletic season, in summer, when the athletes were undertaking extensive endurance training to enhance aerobic capacity, (b) during the winter sports season, in early winter, when endurance and athletic training were being undertaken, and (c) after the winter sports season, in spring, when the athletes were resting (detraining for a month) . The mean value of the maximal oxygen uptake in each training period was (a) 65.4 (SD 4.6) mL·kg-1·min-1, (b) 63.1 (SD 5.5) mL· kg-1·min-1, and (c) 58.3 (SD 5.8) mL·kg-1·min-1, respectively. Following maximal exercise, acute peripheral leukocytosis due to lymphocytosis and neutrophila was observed in every period. The capacity of isolated neutrophils to produce reactive oxygen species upon stimulation with opsonized zymosan measure by luminol-dependent chemiluminescence (LDCL) was significantly enhanced after maximal exercise before and during the athletic season. However, the degree of enhancement was smaller during after-season detraining, suggesting that the conditioning state affected the exercise-induced changes in neutophil functional status. Serum opsonic activity also showed a similar pattern. As for the chronic effects of training, the resting values of the neutrophil count, especially the segmented neutrophil count, the neutrophil LDCL response and the serum IgG level, declined significantly in the pre-season training period. Since the subjects were engaged in exhaustive endurance training under heat exposure at that time, the nonspecific immune status might have been partially compromised due to chronic overload.

Effects of Acute Endurance Exercise and 8 Week Training on the Production of Reactive Oxygen Species from Neutrophils in Untrained Men.

We investigated the effects of acute endurance exercise and habitual physical activity for health maintenance on human neutrophil function in 12 untrained men. The acute exercise condition was a continuous exercise for 90 minutes at the intensity of 50% and 55% of maximal oxygen uptake (VO2max) on an ergometer. The training program was 3 km jogging three times per week for 8 weeks. The capacity of neutrophils to produce reactive oxygen species (ROS) was detected with lucigenin-dependent chemiluminescence (LgCL) and luminol-dependent chemiluminescence (LmCL) on stimulation with opsonized zymosan (OZ) and phorbol myristate acetate (PMA). As for the acute exercise effects, both LgCL and LmCL responses of neutrophils, stimulated using PMA consistently increased after exercise at 50%VO2max, whereas those stimulated with OZ remained unchanged. At 55%VO2max, LgCL responses to both stimulants increase maximally 1 h after exercise, and then decreased 3 h after exercise, whereas LmCL responses to both stimulants increased continuously after exercise at 55%VO2max. These phenomena observed at 55%VO2max compared to 50%VO2max suggests the improved capacity of producing ROS neutrophils after exercise. The number of neutrophils also increased maximally 1 h after exercise, due to the mobilization of band neutrophils (shift to the left), suggesting that functional changes was associated with cell mobilization. The increase in the capacity of neutrophils to produce ROS and marked neutrophilia following the acute endurance exercise suggests that a large quantity of ROS may be produced in vivo. As for the training effects, the LgCL and LmCL responses were maintained in the exercise group as compared to the decreased ones in the control group. The difference between the exercise group and the control group was observed only in LgCL response to OZ. Humoral immune factors (IgG, IgA, IgM, C3, C4) and serum opsonic activity were also unaltered. These phenomena suggest that homeostasis might be kept constant in terms of immunity through regular physical activity.

The effects of interferon-alpha on oxygen radical production by human neutrophils

This study was done to determine if the production and metabolism of reactive oxygen species from human neutrophils were modulated by the treatment of interferon-alpha (IFN-alpha). Luminol-dependent Chemiluminescence (LmCL) responses were inhibited by a high concentration of IFN-alpha (more than 1 x 10(4) IU/ml) when opsonized zymosan (OZ) and phorbol 12-myristate 13-acetate (PMA) were used as stimulants. However, these responses were increased by 1 x 10(3) IU/ml of IFN-alpha with Ca(2+)-ionophore A23187 stimulation. Lucigenin-dependent Chemiluminescence (LgCL) responses were inhibited by all concentrations. These findings suggest the possibility that IFN-alpha inhibits activation of protein kinase C (PKC), whereas the resulting effect might be due to the inhibition of myeloperoxidese (MPO) degranulation. Preincubation of human neutrophils with IFN-alpha for 30, 60 or 120 minutes and subsequent stimulation with OZ, PMA and Ca(2+)-ionophore A23187 caused an increase LgCL responses, while inhibiting LmCL responses. These findings suggest that preincubation of human neutrophils with a high concentration of IFN-alpha might enhance the NADPH-oxidase activity, although a relative increase of LgCL was due to the inhibition MPO degranulation.

Systemic inflammatory responses in acute coronary syndrome: increased activity observed in polymorphonuclear leukocytes but not T lymphocytes

Background: Local inflammation within the coronary arteries is involved in the pathogenesis of acute coronary syndrome. However, the contribution of a systemic inflammatory response to the pathogenesis of this syndrome has not been well characterized. Accordingly, we investigated systemic inflammatory responses in patients with acute coronary syndrome. Methods: A total of 83 patients with ischemic heart disease (15 with stable exertional angina and 68 with acute coronary syndrome) were studied. The luminol-dependent chemiluminescence (CL) response of polymorphonuclear leukocytes (PMNs), which reflects their ability to generate oxygen species, was used as a marker for PMN activation. Soluble interleukin-2 receptor (sIL-2R) levels were measured to assess T-lymphocyte activation. Results: CL counts of whole blood from patients with acute coronary syndrome were twice those of patients with stable angina (2.38±0.22 vs 1.10±0.17×10 6 counts, P<0.05). A comparison of CL counts between patients with unstable angina and those with acute myocardial infarction revealed no significant differences. T-lymphocyte activity, measured by serum sIL-2R, was significantly lower in patients with acute coronary syndrome than those with stable angina (214.3±11.5 vs. 358.3±115.7 U/ml, P<0.05). Conclusions: This investigation shows that there is a systemic increase in PMN activity and a decrease in T-lymphocyte activity in patients with acute coronary syndrome. This contrasts with the pattern of cellular activation seen at sites of local inflammation within atherosclerotic plaques, suggesting that two independent inflammatory processes (local and systemic) may be involved in the pathogenesis of this syndrome.

Effect ofHaemophilus somnuson nitric oxide production and chemiluminescence response of bovine blood monocytes and alveolar macrophages

Haemophilus somnusis able to survive and multiply in bovine blood monocytes (BBM) and alveolar macrophages (BAM), but the mechanisms used byH. somnusto evade killing mechanisms of bovine mononuclear phagocytes are not completely understood. To study the bactericidal ability of bovine mononuclear phagocytes following interaction withH. somnus,in vitroassay systems were developed to detect the luminol-dependent chemiluminescence response (LDCL) and nitric oxide (NO) production of BBM and BAM. Live logarithmically growing or stationary phaseH. somnusinhibited the LDCL of BBM and BAM costimulated with opsonizedStaphylococcus aureus. Inhibition of the LDCL response of BBM and BAM was not mediated by liveH. somnusopsonized with hyperimmune serum, or by killed bacteria.H. somnusstimulated both BBM and BAM to produce NO at levels comparable withEscherichia colilipopolysaccharide. While NO was being produced, viableH. somnuscould still be isolated from the cell cultures. The ability ofH. somnusto inhibit LDCL of both BBM and BAM, and resistance to NO killing may be an important mechanism that contributes to survival of the organism following ingestion by bovine mononuclear phagocytes.

Involvement of both protein kinase C and G proteins in superoxide production after IgE triggering in guinea pig eosinophils

ABSTRACT To study the function and mechanism of eosinophils via the low affinity IgE receptor (FceRII), we examined the production of 0 2 metabolites by measuring the luminol-dependent chemiluminescence (LDCL) response and the generation of cysteinyl leukotrienes. Eosinophils obtained from guinea pig peritoneal fluid sensitized with horse serum were purified. Luminol-dependent chemiluminescence was induced by stimulation with monoclonal anti-CD23 antibody, but not by mouse serum (controls). The mean (±SEM) value of LDCL was 20.6±1.3X10 3 c.p.m. This reaction consisted of an initial rapid phase and a propagation phase and ended within lOmin. Guinea pig eosinophils were histochemically stained with monoclonal anti-CD23 antibody. The major product generated in the LDCL response was superoxide, as determined by the measurement of superoxide by cytochrome c reduction and the complete inhibitory effect of superoxide dismutase on the LDCL response. Pretreatment with either pertussis toxin or cholera toxin inhibited the LDCL reaction. Depletion of bivalent ions by EDTA inhibited this response and the protein kinase C inhibitor D-sphingosin inhibited both 1-oleoyl-2-acetyl-glycerol-induced and FcϵRII-mediated LDCL. These findings suggest that the NADPH-protein kinase C pathway may be involved in the FceRII-mediated LDCL response in guinea pig eosinophils.

Inhibitory Factors of Serum Opsonic Activity in Serum from Patients with Chronic Renal Failure

We investigated the mechanism of impaired serum opsonic activity in patients suffering from chronic renal failure (CRF). Prehemodialysis pooled serum from CRF patients was fractionated using Sephadex G-50 gel chromatography, and the effects of the obtained fractions on serum opsonic activity were examined using luminol-dependent chemiluminescence responses. Number 25–30 fractions in the prehemodialysis serum contained factors that may inhibit serum opsonic activity. The presumed molecular weight of these fractions is between 300 and 2800 daltons. These findings indicate that the inhibitory factors of serum opsonic activity may belong to middle molecules.

Augmented chemiluminescence response of bronchoalveolar lavage cells in calves receiving repeated daily sprayings of ammonia mist into the nasal cavities.

The effect of ammonia inhalation on the luminol-dependent chemiluminescence response of bronchoalveolar lavage (BAL) cells was investigated in clinically normal calves receiving eight ml of ammonia water (5,000 ppm) in the form of aerosol sprayed into the nasal cavities (four ml into each nostril) once a day for two weeks. The chemiluminescence level of BAL cells was augmented following the sprayings of ammonia compared with prior to exposure. The level still remained high one week after the exposure was removed, but showed recovery after two weeks.

Interaction of nitric oxide synthase inhibitors and their D-enantiomers with rat neutrophil luminol dependent chemiluminescence response.

1. Formyl-methionyl-leucyl-phenylalanine (FMLP) or arachidonic acid (AA) induced luminol dependent chemiluminescence (LCL) response of rat polymorphonuclear leukocytes (PMNLs) was found to be inhibited by nitric oxide synthease inhibitors and their D-enantiomers. 2. Rat PMNLs LCL response was inhibited by NG-nitro-L-arginine methyl ester (L-NAME), D-NAME, NG-monomethyl-L-arginine (L-NMMA) or D-NMMA, in a concentration- and time-dependent manner. 3. It was observed that both L- and D-enantiomers of the arginine analogues (1000 microM) did not inhibit AA induced lucigenin-dependent chemiluminescence (LUCDCL) response and cytochrome c reduction, used for estimating the NADPH-oxidase activity in the cells and in the cell free system, respectively. 4. None of the L- and D-enantiomers had any effect on either rat basal PMNLs or AA-induced oxygen consumption. 5. In addition, neither the L nor D-enantiomers of NAME altered either AA-induced release or the activity of myeloperoxidase from rat PMNLs azurophilic granules. 6. The results obtained indicate that the attenuation of the LCL response by L- and D-enantiomers of arginine analogues, is a non-specific effect as there was no inhibition of NADPH-oxidase and MPO activity, MPO release or oxygen consumption. Therefore, the data obtained indicate that these agents should be used with caution to analyse the role of nitric oxide in rat PMNLs LCL response.

Role of leukotriene B4 in the interleukin-4-induced human mononuclear phagocyte activation.

Interleukin-4 (IL-4) induced a time- and dose-dependent production of leukotriene B4 (LTB4) by human resting monocytes indicating that IL-4 induced the activation of the 5-lipoxygenase pathway in resting human monocytes. Maximal effect was observed in the presence of 10 ng/ml IL-4, and in kinetics experiments LTB4 production plateaued 40 min after the onset of stimulation. When stimulated for 48 hr with IL-4, resting human monocytes expressed and released the low-affinity receptor for IgE (CD23) and were partially inhibited in the presence of a highly non-redox 5-lipoxygenase inhibitor (BW B70C), suggesting that the production of LTB4 partially contributed to the IL-4-induced CD23 expression and release. This hypothesis was strengthened by the fact that exogenous LTB4 (10 nM) was found to increase the effect of a suboptimal dose of IL-4 (1 ng/ml). In addition to these phenotypical changes, IL-4 primed the phorbol-12-myristate-13-acetate (PMA)-induced luminol-dependent chemiluminescence response (LDCL) by normal human monocytes, this priming effect being abrogated in the presence of BW B70C. Taken together, these data indicated that IL-4 induced the production of LTB4 by activation of the 5-lipoxygenase pathway in human monocytes, and that the activation of this pathway could upregulate the expression and release of CD23 and the respiratory burst of these cells.

Oxygen-dependent and -independent mechanisms of renal injury in experimental ascending pyelonephritis

Pyelonephritis is the most common urinary tract infection affecting females of all age groups. Despite concerted efforts the mechanism of renal injury in pyelonephritis is not clearly understood. In the present study we have made an attempt to characterise the mediators of inflammatory insult in an experimental model of ascending pyelonephritis. Mice infected with Escherichia coli O6:K13:H1 were sacrificed at 2, 7 and 14 days post-infection. Luminol-dependent chemiluminescence response, NADPH oxidase, acid phosphatase, β-glucuronidase and N-acetyl-β- d-glucosaminidase activities were monitored in circulating as well as renal phagocytic cells in order to determine the role of reactive oxygen species and lysosomal enzymes in genesis of renal injury. We have demonstrated that reactive oxygen species are generated at the initiation of infection and the levels increase progressively during the course of infection. While intracellular release of lysosomal enzymes was seen in all groups, extracellular release was primarily observed at 7 and 14 days post-infection only. The results indicate that while reactive oxygen species play a significant role in tissue injury during all stages of infection, lysosomal enzyme release in extracellular milieu augments tissue destruction at later stages only.

Oxygen-dependent and -independent mechanisms of renal injury in experimental ascending pyelonephritis.

Pyelonephritis is the most common urinary tract infection affecting females of all age groups. Despite concerted efforts the mechanism of renal injury in pyelonephritis is not clearly understood. In the present study we have made an attempt to characterise the mediators of inflammatory insult in an experimental model of ascending pyelonephritis. Mice infected with Escherichia coli O6:K13:H1 were sacrificed at 2, 7 and 14 days post-infection. Luminol-dependent chemiluminescence response, NADPH oxidase, acid phosphatase, beta-glucuronidase and N-acetyl-beta-D-glucosaminidase activities were monitored in circulating as well as renal phagocytic cells in order to determine the role of reactive oxygen species and lysosomal enzymes in genesis of renal injury. We have demonstrated that reactive oxygen species are generated at the initiation of infection and the levels increase progressively during the course of infection. While intracellular release of lysosomal enzymes was seen in all groups, extracellular release was primarily observed at 7 and 14 days post-infection only. The results indicate that while reactive oxygen species play a significant role in tissue injury during all stages of infection, lysosomal enzyme release in extracellular milieu augments tissue destruction at later stages only.

Formylmethionyl-leucyl-phenylalanine-induced chemiluminescence responses in bovine polymorphonuclear leukocytes

Isolated bovine polymorphonuclear leukocytes (PMNL) show a biphasic luminol-dependent chemiluminescence response, and when exposed to high concentrations (2 × 10 −4 M) of the chemotactic peptide formylmethionyl-leucyl-phenylalanine (f-Met-Leu-Phe), the second emission peak is enhanced. This response was increased in magnitude by incubating PMNL at room temperature before stimulation with f-Met-Leu-Phe. Pre-exposure of bovine PMNL to myeloperoxidase (MPO) also enhanced their receptiveness to the chemotactic peptide, indicating that the MPO-hydrogen peroxide system can modulate the bovine PMNL response to chemotactic factors. The results demonstrate that bovine PMNL are stimulated by the chemotactic peptides to participate in inflammatory processes.

Restorative effect of ofloxacin on inhibited chemiluminescence response of PMNs by sera from uraemic patients.

Uraemic patients are thought to be susceptible to infection because of dysfunction of defence mechanisms, including polymorphonuclear leuco­ cytes (PMNs). The bactericidal effect of PMNs largely depends upon the production of reactive oxygen metabolites during the respiratory burst. Therefore, determination of the amount of reactive oxygen metabolites after stimulation by phorbol myristate acetate (PMA) is thought to be a useful method for investigating PMN function in patients undergoing haemodialysis. We previously reported that ofloxacin enhanced the luminol-dependent chemiluminescence (CL) response of PMNs, and an enhanced CL response was also observed under hyperosmotic conditions produced by high concentrations of urea and NaCl, in an in vitro model of renal medulla}l] In the pres­ ent study, we examined the effect of ofloxacin on the reduced CL response produced by sera of haemodialysis patients. Sera were obtained from 41 patients (32 males, 9 females) with renal failure. All were receiving long term haemodialysis. Sera from 21 healthy vol­ unteers were used as a control. PMNs were obtained from the peripheral blood of one healthy volunteer. Blood was collected in 3% citric acid and allowed to sediment in dextran for 1 hour. Each leucocyte­ rich supernatant was separated by centrifuga­ tion on Histopaque®. The luminol-dependent CL response was measured with a luminometer (Biolumat® model 9505, Berthold, Germany) after stimulation with PMA. The reaction mixture con­ sisted of 100111 of serum, 500111 of the cell suspen­ sion (2 x 106 cells/rnl), 2 x 10-6 mollL luminol, and 500111 PMA (2 x 10-3 mg/ml). The light reaction was traced for 30 minutes. The integral of the CL count was automatically calculated from the curve, and the CL response was expressed as log cpm, or as the percentage chemiluminescence compared

Modulation of Rat Peripheral Polymorphonuclear Leukocyte Response by Nitric Oxide and Arginine

The effect of nitric oxide (NO) on the luminol-dependent chemiluminescence (LCL) response of rat polymorphonuclear leukocytes (PMNLs) was analyzed by using sodium nitroprusside (SNP), a NO donor, and L-arginine (L-arg), a NO precursor. A significant reduction in the LCL intensity was observed in presence of SNP (100 mumol/L) or L-arg (5 or 10 mmol/L) in arachidonic acid (AA) phorbol ester (PMA) and formyl-methionyl-leucyl-phenylalanine stimulated PMNLs. However, opsonized zymosan-induced LCL was not attenuated significantly. Reduction in hydroxyl radical and superoxide generation was also observed in SNP- or L-arg-pretreated cells. D-Arg (10 mmol/L) pretreatment did not inhibit PMNLs' LCL response. Furthermore, methylene blue (5 mumol/L) and L-NG-mono methyl-L-arginine (100 or 300 mumol/L) significantly attenuated the LCL response, as induced by various agonists. Cyclic GMP did not alter the reactive oxygen species generation from rat PMNLs. In addition, AA-induced release of myeloperoxidase, a marker of azurophilic granules, was found to be enhanced in L-arg- (10 mmol/L) pretreated PMNLs. The results suggest that NO inhibits free radical generation from rat PMNLs.

Modulation of rat peripheral polymorphonuclear leukocyte response by nitric oxide and arginine

The effect of nitric oxide (NO) on the luminol-dependent chemiluminescence (LCL) response of rat polymorphonuclear leukocytes (PMNLs) was analyzed by using sodium nitroprusside (SNP), a NO donor, and L-arginine (L-arg), a NO precursor. A significant reduction in the LCL intensity was observed in presence of SNP (100 mumol/L) or L-arg (5 or 10 mmol/L) in arachidonic acid (AA) phorbol ester (PMA) and formyl- methionyl-leucyl-phenylalanine stimulated PMNLs. However, opsonized zymosan-induced LCL was not attenuated significantly. Reduction in hydroxyl radical and superoxide generation was also observed in SNP- or L-arg-pretreated cells. D-Arg (10 mmol/L) pretreatment did not inhibit PMNLs' LCL response. Furthermore, methylene blue (5 mumol/L) and L-NG- mono methyl-L-arginine (100 or 300 mumol/L) significantly attenuated the LCL response, as induced by various agonists. Cyclic GMP did not alter the reactive oxygen species generation from rat PMNLs. In addition, AA-induced release of myeloperoxidase, a marker of azurophilic granules, was found to be enhanced in L-arg- (10 mmol/L) pretreated PMNLs. The results suggest that NO inhibits free radical generation from rat PMNLs.

Bovine neutrophil chemiluminescence is preferentially stimulated by homologous IL-1, but inhibited by the human IL-1 receptor antagonist

Previous studies have indicated that certain types of bovine cells preferentially respond to bovine interleukin-1 (IL-1) compared with IL-1 from other mammalian species. In this study, we demonstrate that bovine neutrophils undergo a substantially greater luminol-dependent chemiluminescence response to bovine IL-1 β than to human IL-1 α, human IL-1 β, or murine IL-1 α. Likewise, approximately 1000-fold less bovine IL-1 β than human IL-1 β was required to prime bovine neutrophils for an enhanced luminol-dependent chemiluminescence response to opsonized zymosan particles. A recombinant human IL-1 receptor antagonist was a potent inhibitor of bovine neutrophil stimulation and priming by homologous and heterologous IL-1. These data indicate a hierarchy amongst members of the IL-1 family in terms of their relative abilities to modulate the functional activation of bovine neutrophils.