Characterization of sulfidopeptide leukotriene responses in sheep tracheal smooth muscle in vitro.

We have investigated the effects of leukotrienes (LTs) on isolated tracheal smooth muscle from sheep sensitive to Ascaris suum antigen. LTC4 and LTD4 produced dose-dependent contractions of sheep trachea, but LTE4 was virtually inactive. YM-17690, a non-analogous LT agonist, produced no contractile response up to 100 microM. Indomethacin (5 microM) had no effect on LTC4- and LTD4-induced contractions. L-Serine borate (45 mM), an inhibitor of gamma-glutamyl transpeptidase, shifted the dose-response curve of LTC4 to the left by 161-fold, and L-cysteine (6 mM), an inhibitor of aminopeptidase, shifted the dose-response curves of LTC4 and LTD4 to the left by 67- and 23-fold, respectively. YM-16638 (1 microM), an LT antagonist, shifted the dose-response curves of LTC4 and LTD4 to the right with pKB values of 6.57 and 7.13, respectively. YM-16638 did not affect LTC4-induced contractions of L-serine borate-treated tissues, indicating that the compound acts only on LTD4 receptors in sheep trachea, LTE4 (1 microM) shifted the dose-response curves of LTC4 and LTD4 to the right with pKB values of 6.87 and 7.31, respectively. YM-17690 (10 microM) showed effects similar to LTE4, suggesting that the compound acts as an LTE4 agonist in sheep trachea. These results suggest that in sheep tracheal smooth muscle (a) LTC4 and LTD4 produce contractions, (b) these LT-induced contractions are not mediated by cyclooxygenase products, (c) LTC4 is converted to LTD4 and then to LTE4, and (d) the potency of the LTC4- and LTD4-induced contractions is increased when their conversion to LTE4 is inhibited.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of synthetic leukotrienes on tracheal microvascular permeability

The effect of synthetic leukotrienes (LT) C4, D4 and E4 on the permeability of the airway microvasculature to plasma albumin was quantitatively evaluated using an in situ guinea pig tracheal model. Vascular permeability was measured as extravascular albumin content by employing 125I-bovine serum albumin and, in order to correct for blood volume, 51Cr-erythrocytes were used. Intratracheal injection of synthetic LTC4, LTD4 and LTE4 (0.1-1000 ng) produced dose-dependent increases in tracheal extravascular albumin content. The leukotrienes were approximately 100-1000 fold more potent than histamine, although histamine did produce a greater maximal increase in extravascular albumin than the leukotrienes. Methacholine did not increase extravascular albumin content. The microvascular permeability effect of LTD4 was antagonized by FPL 55712 but not by mepyramine; conversely, the effect of histamine was antagonized by mepyramine and not by FPL 55712. Additionally, indomethacin did not alter the LTD4-induced increases in tracheal vascular permeability. These results suggest that the effect of LTD4 on tracheal microvascular permeability is directly mediated and is not the indirect result of cholinergic stimulation, histamine release or de novo synthesis of cyclooxygenase products.     

Pharmacology of peptide leukotrienes on ferret isolated airway smooth muscle

The contractile activities of peptide leukotrienes (LT) on isolated spiral strips of ferret trachea were characterized pharmacologically. LTC4 and LTD4 contracted ferret tracheal strips in a concentration-related manner and were 3- to 8-fold more potent than carbachol. In contrast, high concentrations of LTE4 evoked either weak contractions or none at all, whereas LTC4 and D4 were partial agonists compared to carbachol. In tissues which were unresponsive to LTE4, this compound antagonized contractile responses to LTC4 and D4 in an apparently competitive manner: Carbachol-induced contractions were not altered by LTE4. The cyclooxygenase inhibitor, indomethacin (5 microM), LT antagonist, FPL55712 (10 microM), atropine (1 microM), phenoxybenzamine (10 microM), and LTB4 (10 microM) failed to alter LTC4 and D4 concentration-response curves. The results indicate that ferret trachea is sensitive to the contractile activity of LTC4 and LTD4 but not LTE4. The LT-induced contractions appear to be mediated by a direct action of the LT rather than indirectly through release of secondary mediators such as thromboxane, prostaglandin, or acetylcholine. LT receptors in ferret trachea are insensitive to FPL55712 but are antagonized by LTE4.     

Purification and biochemical characteristics of pectinesterase from Malatya apricot (Prunus armeniaca L.)

Pectinesterase (PE) in Malatya apricot pulp (Prunus armeniaca L.) was extracted and purified through (NH(4))(2)SO(4) precipitation, dialysis, and DEAE-Sephadex gel filtration chromatography. The samples obtained from the dialysis procedure, named partially purified enzyme, were used for characterization of the apricot pectinesterase. The effect of various factors such as pH, temperature, heat, and storage stability on the partially purified apricot PE enzyme was investigated. Optimum pH value was 9.0 for PE with 1% pectin in 0.1 N NaCl (w/v). The optimum temperature for apricot PE was found to be 60 degrees C on standard analysis conditions. Heat inactivation studies showed a decrease in enzymatic activity at temperatures above 70 degrees C. Km and V(max) values were 0.77 mM and 1.75 micromol min(-1) mg(-1) for apricot PE. Five inhibitors were tested in the study; the most effective inhibitor was found to be sodium carbonate (100% inhibition). The order of inhibitory effectiveness was: Na(2)CO(3), iodine, lauril sulphate, AgNO(3), EDTA. Thermal inactivation data indicated that apparent activation energy with pectin substrate was 2.96 kcal mol(-1) for the enzyme. Ascorbic acid, CaCl(2), and KCl showed activatory effect on the apricot PE enzyme.     

Effects of piriprost (U-60, 257B) and leukotrienes on alkaline phosphatase activity of rat endometrial stromal cells in vitro.

The present study investigated the effects of piriprost (U-60,257B; an inhibitor of LT synthesis) and various LTs on alkaline phosphatase (ALP) activity of rat endometrial stromal cells in vitro. Mature ovariectomized rats were pretreated with hormones to sensitize their uteri for the decidual cell reaction. Endometrial stromal cells were isolated and cultured for up to 72 hr with various treatments. The ALP activity in all experiments was significantly (p less than 0.01) higher at 72 hr than at 24 hr, irrespective of treatment. We examined the effects of 100 microM piriprost, with or without 1 microM LTB4, 0.01 microM LTC4, 0.1 microM LTD4 or 0.001 microM LTE4 on ALP activity. At 72 hr, as indicated by analyses of variance, there were significant interactions (p less than 0.01) between the effects of piriprost and the LTs. Piriprost by itself increased (p less than 0.01) ALP activity in all experiments, and a further increase (p less than 0.01) in ALP activity was observed when either LTB4, LTC4, LTD4 or LTE4 was added with piriprost. LTB4, LTD4, or LTE4 alone had inhibitory effects (p less than 0.01) while LTC4 alone had no effect. These studies suggest LTs may be involved in decidualization which, in vitro, is accompanied by an increase in endometrial ALP activity. However the exact role of LTs is still unclear.     

Heat shock induces alterations of the lipoxygenase pathway in human polymorphonuclear granulocytes

We have investigated the effect of the heat shock response on the leukotriene generation, chemotaxis, and generation of oxygen radicals of human polymorphonuclear granulocytes (PMNs) by preincubating the PMNs at 42 degrees C. Subsequently, the different test systems were performed at 37 degrees C. As we confirmed by the release of lactate dehydrogenase and beta-glucuronidase the elevated temperatures did not result in cytotoxic or degranulating processes. After heat shock treatment the generation of leukotrienes induced by the Ca(++)-ionophore A23187, fMLP or opsonized zymosan was inhibited in a time and temperature dependent manner (preincubation phase) as was measured by HPLC-analysis. In contrast, the conversion of 14C-arachidonic acid revealed the generation of LTB4, 5-HPETE and 5-HETE solely as a result of the preincubation at 42 degrees C without any further stimulation. In addition, the chemiluminescence response induced by opsonized zymosan and the chemotaxis against C5a and LTB4 was clearly inhibited after heat shock treatment. With regard to enzyme activities of the heat treated PMNs the protein kinase C activities were enhanced whereas the LTD4-dipeptidase and the LTB4-omega-hydroxylase were not affected.     

Alternative complement pathway-dependent ingestion of fluolite particles by human granulocytes

Fluorescent particles (Fluolite) with an average size of 0.1 micrometers were ingested by human granulocytes after incubation in fresh normal human serum (NHS). Ingestion was assessed by visual counting in a fluorescent microscope of cells containing particles. Ingestion required fresh normal serum and did not occur when serum was heated for 30 min at 50 degrees C or in the presence of ethylenediaminetetraacetic acid (EDTA). It did not occur in serum genetically deficient in C3b inactivator or in C3. Phagocytic activity was restored to C3-deficient serum by purified human C3 and to heat inactivated serum by purified factor B. Opsonic activity was present in NHS containing 5 mM Mg++ and 10 mM ethyleneglycoltetraacetic acid (EGTA) and in human serum genetically deficient in human C components C2 and C5. Agammaglobulinemic sera had normal opsonic activity. Opsonization of particles in this system is mediated through the alternative pathway of C activation, and its measurement serves as a simple quantitative functional assay for this system.     

Purification and characterization of a new arginine carboxypeptidase in human serum

A carboxypeptidase capable of cleaving basic amino acids from synthetic peptide substrates is present in fresh human serum, and not in human heparinized plasma. Its activity is generated during the process of coagulation. Because of its unstability at room temperature and at 37 degrees C, we named it unstable carboxypeptidase (carboxypeptidase U). Carboxypeptidase U was partially purified from fresh human serum by chromatography on DEAE-cellulose and Mono-Q sepharose and was found to be a 435 kDa protein. We compared this enzyme with carboxypeptidase N, purified from human serum by a two-step affinity chromatography on arginine-Sepharose 4B, followed by ion-exchange chromatography on Mono-Q sepharose. Carboxypeptidase U cleaves hippuryl-L-arginine and hippuryl-L-lysine, but at a different relative rate than carboxypeptidase N, and has no esterase activity on hippuryl-L-argininic acid. Its activity was inhibited by o-phenanthroline, DL-2-mercaptomethyl-3-guanidinoethylthiopropanoic acid, CoCl2, 2-mercaptoethanol, dithiothreitol and 4-chloromercuribenzoic acid. These characteristics differentiate carboxypeptidase U from carboxypeptidase N and other known carboxypeptidases.     

大肠杆菌不耐热肠毒素的表达及其纯化保存策略

编码完整大肠杆菌不耐热肠毒素(LT)的基因被引入pET11c形成pET11-LT,该质粒在E.coli BL21(DE3)中得到较高效率的表达,约46mg/L。用D(+)Immobilized galactose柱可以在很宽的pH范围(pH7.3～10.4)内用多种方法对LT进行纯化且保持其结构完整。溶于TEAN(pH7.3)或碳酸盐缓冲液(pH10.4)的LT,冻干后保存于4℃,可长久保持其完整结构,此为保存LT的较好策略。与GM1结合实验、CHO细胞及Patentmouse毒性检测实验证明纯化的LT具有生物学活性。     

Purification and properties of growth inhibitor from normal rabbit serum.

It was previously found that rabbit serum contains a growth-inhibitory substance for a tumorigenic rat liver cell line RSV-BRL. In the present study, the growth inhibitor was purified from normal rabbit serum to show a homogeneous protein band with a molecular weight (Mr) of 56 k on SDS-polyacrylamide gel electrophoresis under non-reducing conditions. The purified growth inhibitor, tentatively named rabbit serum-derived growth inhibitor (RSGI), potently inhibited the growth of RSV-BRL and nine kinds of other cell lines including three human tumor cell lines at a concentration of 20 ng/ml or higher. The growth-inhibitory effect of RSGI was reversible and appeared to be cytostatic rather than cytotoxic. RSGI was stable to heating at 56 degrees C for 30 min or treatment with 0.1 M 2-mercaptoethanol, but labile to heating at 100 degrees C for 3 min or treatment with 1 M acetic acid (pH 2.3), 6 M urea, 50% (v/v) 1-propanol, or 0.1% (w/v) trypsin. These properties of RSGI suggested that it was different from type beta transforming growth factors, tumor necrosis factor-alpha, and other known growth-regulatory factors.     

An acidic protease from the grass carp intestine (Ctenopharyngodon idellus)

The acidic Protease was extracted from the intestine of the grass carp (Ctenopharyngodon idellus) by 0.1 M sodium phosphate buffer, pH 7.0 at 4 degrees C after neat intestine was defatted with acetone, and partially purified by ammonium sulfate precipitation, gel filtration chromatography and ionic exchange chromatography. SDS-PAGE electrophoresis showed that the enzyme was homogeneous with a relative molecular mass of 28,500. Substrate-PAGE at pH7.0 showed that the purified acidic protease has only an active component. Specificity and inhibiting assays showed that it should be a cathepsin D. The optimal pH and optimal temperature of the enzyme were pH2.5 and 37 degrees C, respectively. It retained only 20% of its initial activity after incubating at 50 degrees C for 30 min. The enzyme lost 81% of its activity after incubation with pepstatin A at room temperature, but was not inhibited by soybean trypsin inhibitor or phenylmethylsulfonyl fluoride (PMSF). Its V(max) and K(m) values were determined to be 3.57 mg/mL and 0.75 min(-1), respectively.     

Modulation of fibroblast proliferation by sulfidopeptide leukotrienes: effect of indomethacin

Because infiltration of mononuclear cells and fibroblast proliferation are associated in chronic inflammatory lesions, we tested the hypothesis that leukotrienes (LT), a product of activated mononuclear cells, may modulate fibroblast growth. Proliferation of cultured human skin fibroblasts was estimated by [3H]thymidine incorporation and cell count at increasing concentrations (0.1 nM to 0.1 microM) of LTC4 or LTD4. LTC4 and LTD4 stimulated cell growth in a dose-dependent manner only in the presence of 50 microM indomethacin. Under similar conditions, LTE4 but not LTB4 (0.1 microM) was active. Both asynchronous, growing cells and synchronous, quiescent cells were sensitive to LT when prostaglandin (PG) synthesis was suppressed by indomethacin. Other blockers of cyclooxygenase such as ibuprofen and aspirin exhibited identical permissive activity, and the effect of indomethacin was totally abolished by addition of PGE2. LTC4 modified neither [3H]arachidonic acid release from prelabeled fibroblasts nor PGE2 production by fibroblasts. These results demonstrate that the sulfidopeptide LT stimulate fibroblast proliferation only when the endogenous synthesis of PG is blocked, but they do not enhance the synthesis of PG in their target cells showing no evidence for a negative feed-back loop. Nevertheless, it seems likely that the initiation and development of the fibrotic process in the different tissues depends in part on the local balance between PG and LT productions.     

Leukotrienes C4, D4, and E4 in fetal lamb tracheal fluid

Previously, we demonstrated that either putative leukotriene receptor antagonists or a synthesis inhibitor markedly decreased pulmonary vascular resistance in the near-term fetal lamb and concluded that leukotrienes may play a role in maintaining the high pulmonary vascular resistance in the fetus. To further investigate the role of leukotrienes, we measured concentrations of leukotriene (LT) C4, LTD4, and LTE4 in 17 tracheal fluid samples from 8 of 9 near-term (129-139 days, term = 145 days), chronically-catheterized, fetal lambs during normoxia to evaluate their possible role in regulating resting tone and in seven of the nine before and during hypoxia to evaluate their possible role in hypoxic vasoconstriction. The tracheal fluid samples collected by gravity over 1-3 min, on ice, were immediately treated with cold ethanol, centrifuged, and the supernatant covered with N2 and stored in a -70 degrees C freezer for a maximum of 3 weeks. Purification and separation of leukotrienes was done by reverse-phase high performance liquid chromatography using a gradient elution method, and fractions corresponding to LTC4, LTD4, and LTE4 standards were quantified immediately by radioimmunoassay. During normoxia (descending aortic PaO2 2.9 +/- 0.3 kPa [21.5 +/- 2.5 mmHg]; mean +/- SD), all 3 leukotrienes were detected in 16 of the 17 samples: LTC4 29 +/- 28 pg/ml (range 0-119 pg/ml); LTD4 66 +/- 51 pg/ml (range 9-177 pg/ml); and LTE4 43 +/- 50 pg/ml (range 0-204 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

Caldolase, a chelator-insensitive extracellular serine proteinase from a Thermus spp.

An extracellular alkaline serine proteinase from Thermus strain ToK3 was isolated and purified to homogeneity by (NH4)2SO4 precipitation followed by ion-exchange chromatography on DEAE-cellulose and QAE-Sephadex, affinity chromatography on N alpha-benzyloxycarbonyl-D-phenylalanyl-triethylenetetraminyl-Sepha rose 4B and gel-filtration chromatography on Sephadex G-75. The purified enzyme had a pI of 8.9 and an Mr determined by gel-permeation chromatography of 25,000. The specific activity was about 37,700 proteolytic units/mg with casein as substrate, and the pH optimum was 9.5. Proteolytic activity was inhibited by low concentrations of di-isopropyl phosphorofluoridate and phenylmethanesulphonyl fluoride, but was unaffected by EDTA, EGTA, o-phenanthroline, N-ethyl-5-phenylisoxazolium-3'-sulphonate, N alpha-p-tosyl-L-phenylalanylchloromethane, N alpha-p-tosyl-L-lysylchloromethane, trypsin inhibitors and pepstatin A. The enzyme contained approx. 10% carbohydrate and four disulphide bonds. No Ca2+, Zn2+ or free thiol groups were detected. It hydrolysed several native and dye-linked proteins and synthetic chromogenic peptides and esters. The enzyme was very thermostable (half-life values were 840 min at 80 degrees C, 45 min at 90 degrees C and 5 min at 100 degrees C). The enzyme was unstable at low ionic strength: after 60 min at 75 degrees C in 0.1 M-Tris/acetate buffer, pH 8, only 20% activity remained, compared with no loss in 0.1 M-Tris/acetate buffer, pH 8, containing 0.4 M-NaCl.     

Leukotriene formation by eosinophil leukocytes. Analysis with ion-pair high pressure liquid chromatography and effect of the respiratory burst

In this paper, we describe ion-pair reverse-phase high pressure liquid chromatography, a novel, high-resolution method for the separation of leukotrienes. Using this technique, we have studied the production and release of leukotrienes from purified horse eosinophil leukocytes following stimulation with the ionophore A23187. At least 11 different metabolites with spectroscopical characteristics of leukotrienes were resolved. Four of them exhibited the biological activity of the slow-reacting substance an LTC 4/LTD 4 spectra with absorption maxima at 278/281 nm. The other metabolites were virtually devoid of slow-reacting substance activity and exhibited LTB 4 spectra with maxima at 269/271 nm. Since ionophore A23187, under our experimental conditions, induced a respiratory burst in the eosinophils, two modifies of this response, 2-deoxyglucose, an inhibitor of glucose metabolism and catalase, a scavenger of hydrogen peroxide, were used to investigate the influence of the burst on leukotriene generation. An overall inhibition of leukotriene release was induced by 2-deoxyglucose. Catalase strongly decreased the formation of LTB 4 and its stereoisomers and correspondingly enhanced the formation of LTC 4 and LTD 4. On the other hand, the increase of glucose in the medium augmented the production of B4-type leukotrienes while decreasing that of LTC 4 and LTD 4. These results indicate that the respiratory burst is involved in leukotriene synthesis by eosinophil leukocytes.     

Metabolism of leukotriene D4 by rat peritoneal mast cells

Metabolism of sulfidopeptide leukotrienes, leukotrienes (LT) C4 and D4 by rat peritoneal mast cells was studied. Rat peritoneal mast cells converted LTD4 to LTE4 but not LTC4 to LTD4. The LTD4-metabolizing activity was equally distributed on the cell surface and inside cells, but not released to the extracellular milieu even when a considerable portion of histamine and the secretory granule enzymes were released. Among various enzyme inhibitors examined, o-phenanthroline, a metal chelator, and dithiothreitol significantly suppressed the LTD4-metabolizing activity of mast cell. These results would suggest that some metalloenzyme located on the cell surface is involved in the conversion of LTD4 to LTE4 by rat peritoneal mast cells.     

ATP-dependent leukotriene export from mastocytoma cells

The biosynthesis of leukotrienes (LT) C4 and B4 is followed by an export of these mediators into the extracellular space. This transport was characterized using plasma membrane vesicles prepared from mastocytoma cells and identified as an ATP-dependent primary active process. The apparent Km-values were 110 nM for LTC4 and 48 microM for ATP. The transport rate was highest for LTC4, whereas LTD4, LTE4, and N-acetyl-LTE4 were transported with relative rates of 31, 12 and 8%, respectively, at a concentration of 10 nM. LTB4 transport was also dependent on ATP. LTC4 transport was inhibited by LTD4 receptor antagonists (IC50 = 1.0 microM for MK-571 and 1.3 microM for LY245769) and by the inhibitor of leukotriene biosynthesis MK-886 (IC50 = 1.8 microM). The ATP-dependent export carrier for leukotrienes in leukotriene-synthesizing cells represents a novel member of the family of ATP-dependent exit pumps.     

Pharmacology of aerosol leukotriene C4- and D4-induced alteration of pulmonary mechanics in anesthetized cynomolgus monkeys

Aerosol administration of solutions of 900 micrograms/ml of leukotriene C4 (LT) or D4 to cynomolgus monkeys produced dose-dependent, equipotent increases in pulmonary resistance (Rp) and decreases in dynamic lung compliance (Cdyn). Time to peak response was, in part, related to dose and ranged from 4 to 20 min. Both LTC4 and LTD4 were less potent than histamine. Aerosol pretreatment with the cyclooxygenase inhibitor indomethacin had no significant effect on either LTC4 or LTD4 dose-response curves; however, at the highest doses of these agonists a notable, nonsignificant inhibition of effects on both Rp and Cdyn was seen. Intravenous dl-propranolol had no effect on responses to LTD4. Aerosol pretreatment with FPL 55712 significantly (P less than 0.05) inhibited airway responses to both LTC4 and D4. In contrast, an intravenous infusion of FPL 55712 failed to block the bronchospastic activity of LTD4. In conclusion, cynomolgus monkeys are responsive to aerosol administration of LTC4 and LTD4, and the pharmacology of their responses appears to resemble that of man.     

Species differences in the effects of leukotriene D4 on inositol trisphosphate accumulation, cyclic AMP formation and contraction in iris sphincter of the mammalian eye

The effects of leukotriene (LT) D4 on inositol trisphosphate (IP3) accumulation, cAMP formation, and contraction in the iris sphincter smooth muscle of different mammalian species were investigated and functional and biochemical reciprocal interactions between the IP3-Ca2+ and cAMP second messenger systems were demonstrated. The effects of the LT on the biochemical and pharmacological responses are dose- and time-dependent, and are not mediated through the release of acetylcholine or prostaglandins. Addition of LTD4 (0.1-1 microM) to cat and bovine iris sphincters increased IP3 accumulation by 60% of that of the control and induced muscle contraction (the EC50 value for the contractile response in the cat sphincter was 4.8 x 10(-9) M), but had no effect on cAMP formation in these species. In contrast, addition of LTD4 to dog, human, pig, and rabbit sphincters increased cAMP formation by 53-61% of their respective controls, but had no effect on IP3 accumulation and on the contractile state. The rates of formation of LTs in iris sphincters of the different species were found to increase in the following order: bovine less than cat less than human less than dog less than pig less than rabbit. This could suggest that desensitization of LT receptors may in part underlie the species differences observed in the effects of LTD4. We suggest that LTD4 may be involved in regulation of contraction and relaxation in the iris sphincter by increasing IP3 accumulation and consequently Ca2+ mobilization and muscle contraction, and by elevating the level of cAMP which in turn may be involved in the regulation of muscle tension.     

Leukotrienes target F-actin/cofilin-1 to enhance alveolar macrophage anti-fungal activity

Candida albicans is the most common opportunistic fungal pathogen and causes local and systemic disease in immunocompromised patients. Alveolar macrophages (AMs) are pivotal for the clearance of C. albicans from the lung. Activated AMs secrete 5-lipoxygenase-derived leukotrienes (LTs), which in turn enhance phagocytosis and microbicidal activity against a diverse array of pathogens. Our aim was to investigate the role of LTB(4) and LTD(4) in AM antimicrobial functions against C. albicans and the signaling pathways involved. Pharmacologic and genetic inhibition of LT biosynthesis as well as receptor antagonism reduced phagocytosis of C. albicans when compared with untreated or WT controls. Conversely, exogenous LTs of both classes augmented base-line C. albicans phagocytosis by AMs. Although LTB(4) enhanced mainly mannose receptor-dependent fungal ingestion, LTD(4) enhanced mainly dectin-1 receptor-mediated phagocytosis. LT enhancement of yeast ingestion was dependent on protein kinase C-δ (PKCδ) and PI3K but not PKCα and MAPK activation. Both LTs reduced activation of cofilin-1, whereas they enhanced total cellular F-actin; however, LTB(4) accomplished this through the activation of LIM kinases (LIMKs) 1 and 2, whereas LTD(4) did so exclusively via LIMK-2. Finally, both exogenous LTB(4) and LTD(4) enhanced AM fungicidal activity in an NADPH oxidase-dependent manner. Our data identify LTB(4) and LTD(4) as key mediators of innate immunity against C. albicans, which act by both distinct and conserved signaling mechanisms to enhance multiple antimicrobial functions of AMs.