Porcine spermadhesin PSP-I/PSP-II stimulates macrophages to release a neutrophil chemotactic substance: modulation by mast cells

The complex of porcine seminal plasma heterodimers I and II (PSP-I/PSP-II), which are heterodimers of glycosylated spermadhesins, is the major component of porcine seminal fluid. The proinflammatory and immunostimulatory activities of this spermadhesin complex suggest its participation in modulation of the uterine immune activity that may ensure reproductive success. Spermadhesin PSP-I/PSP-II induced the migration of neutrophils into the peritoneal cavity of rats via activation of resident cells. In the present study, we have investigated the involvement of macrophages and mast cells in the neutrophil chemotactic activity of PSP-I/PSP-II and the underlying mechanism. Macrophages and mast cells were isolated, cultured, and stimulated with purified PSP-I/PSP-II. Pharmacological modulation was performed using the glucocorticoid dexamethasone, indomethacin (cyclooxygenase inhibitor), MK886 (leukotriene inhibitor), and the supernatant of spermadhesin-stimulated mast cells. Macrophages stimulated with PSP-I/PSP-II released into the culture supernatant a neutrophil chemotactic substance. This activity was partly inhibited by both dexamethasone (85%) and the supernatant of spermadhesin-stimulated mast cells (74%) but not by indomethacin and MK886. An anti-tumor necrosis factor (TNF) alpha antibody neutralized (by 68%) the neutrophil chemotactic activity of PSP-I/PSP-II-stimulated macrophages. An anti-interleukin (IL)-4 antibody blocked the inhibitory activity of spermadhesin-stimulated mast cells on release of a neutrophil chemotactic substance by PSP-I/PSP-II-stimulated macrophages. As a whole, these data indicate that the neutrophil migration-inducing ability of spermadhesin PSP-I/PSP-II involves the release of the inflammatory cytokine TNFalpha by stimulated macrophages and that this activity is modulated by the lymphokine IL-4 liberated by mast cells. The balance between these two cytokines may control onset of the local inflammatory reaction, avoiding excessive neutrophil recruitment that would lead to tissue damage.     

Structural characterization of the oligosaccharide chains of native and crystallized boar seminal plasma spermadhesin PSP-I and PSP-II glycoforms.

The PSP-I/PSP-II heterodimer is the major protein of boar seminal plasma. Both subunits are glycoproteins of the spermadhesin family and each contains a single N-glycosylation site. After enzymatic release of the oligosaccharides from isolated PSP-I and PSP-II, mainly neutral and monosialylated oligosaccharides, and small amounts of disialylated oligosaccharides, were recovered from both proteins. Twenty-two neutral oligosaccharides, 11 monosialylated glycans and three disialylated carbohydrate chains were characterized using mass spectrometric and NMR techniques. PSP-I and PSP-II share the same glycans but differ in their relative molar ratios. Most glycan structures are proximally alpha1-6-fucosylated, diantennary complex-type bearing nonsialylated or alpha2-6-sialylated N-acetyllactosamine or di-N-acetyllactosamine antennae. The majority of nonsialylated N-acetyllactosamine antennae bear terminal alpha1-3-linked Gal residues. In addition, the N-acetylglucosamine residue of nonsialylated N-acetyl and di-N-acetyllactosamine antennae can be modified by an alpha1-3-linked fucose residue. Structures of higher antennarity, as well as structures 3,6-branched at galactose residues, were found in smaller amounts. In one oligosaccharide, N-acetylneuraminic acid is substituted by N-glycolylneuraminic acid. Mass spectrometric analysis of PSP-I and PSP-II glycoforms isolated from crystallized PSP-I/PSP-II heterodimer showed the coexistence of major PSP-I and PSP-II glycoforms in the hexagonal crystals. Oligosaccharides with the NeuNAcalpha2-6GalNAcbeta1-4GlcNAc-R motif block adhesive and activation-related events mediated by CD22, suggesting a possible immunoregulatory activity for PSP-I/PSP-II.     

Influence of seminal plasma PSP-I/PSP-II spermadhesin on pig gamete interaction

The seminal plasma PSP-I/PSP-II spermadhesin is able to preserve, in vitro, the viability of highly extended boar spermatozoa, suggesting it might be used as a suitable ameliorator for the damaging effects of sperm handling, including in vitro fertilization. However, little is known about the ligand capability of PSP-I/PSP-II as regards the zona pellucida (ZP) or its possible role in gamete interaction. The present study evaluated the effect of the presence of PSP-I/PSP-II (1.5 mg/ml) during in vitro oocyte maturation and also during co-incubation of frozen-thawed boar spermatozoa with either immature (IM) or in vitro matured (IVM) oocytes, either enclosed by cumulus cells or denuded. Exposure of the gametes to the heterodimer during in vitro gamete co-incubation showed a significant blocking effect of sperm penetration rates and a decreased number of spermatozoa per oocyte in both IM and IVM denuded oocytes. Such an effect was not present in cumulus-enclosed oocytes, suggesting the effect could be mediated by exposed ZP receptors. In addition, when PSP-I/PSP-II was added to the IVM medium, oocyte maturation rates were significantly reduced. In conclusion, the results suggest that PSP-I/PSP-II, when present in vitro, blocks sperm-ZP binding.     

Zinc ions induce the unfolding and self-association of boar spermadhesin PSP-I, a protein with a single CUB domain architecture, and promote its binding to heparin

Spermadhesins are a family of seminal plasma proteins composed of a single CUB domain, which appear to be involved in various aspects of the fertilization process in pigs. PSP-I and PSP-II, the most abundant porcine spermadhesins, occur in seminal plasma as noncovalent heterodimers devoid of heparin-binding capability. Of note is the stability of this dimer, which is significantly affected by physiologically relevant conditions such as Zn2+ ions. Here, we show that PSP-I and PSP-II when separated appear to conserve the overall fold of the CUB domain observed in the crystal structure of the PSP-I/PSP-II heterodimer, as concluded from gel filtration, analytical ultracentrifugation, differential scanning calorimetry, and circular dichroism analyses. However, Zn2+ concentrations in the range of those found in boar seminal plasma induce the unfolding and self-association of PSP-I, apparently as a consequence of the exposure of hydrophobic core residues, whereas they have no effect on PSP-II. Remarkably, Zn2+-denatured and self-associated (but not structured monomeric) PSP-I is retained on a heparin column, resembling the behavior of free PSP-I and homologous spermadhesins of the heparin-binding fraction of boar seminal plasma, which also exhibit different aggregation states. Thus, the modulation of the structural organization and heparin-binding ability of PSP-I by Zn2+ might be a physiological phenomenon in seminal plasma.     

Pro-inflammatory effect of Arum maculatum lectin and role of resident cells

Arum maculatum agglutinin (AMA) is a monocot lectin isolated from tubers of Arum maculatum L. (Araceae) which exhibits different specificity towards oligo-mannosidic-type and N-acetyllactosaminic-type glycans. We have investigated the effect of this lectin on the cells of the immune system. Models of neutrophil migration in vivo, neutrophil chemotaxis in vitro and macrophage cultures were used to study the lectin inflammatory activity. When administered into rat peritoneal cavities, AMA (80, 200 and 500 microg/mL/cavity) induced significant and dose-dependent neutrophil migration. This effect was inhibited by incubation with alpha-methyl-d-mannoside. A 83% depletion in the number of resident cells following peritoneal lavage did not reduce the AMA-induced neutrophil migration, as compared to sham animals (not washed). However, pre-treatment with 3% thioglycolate which increases the peritoneal macrophage population by 236%, enhanced the neutrophil migration induced by AMA (200 microg/mL/cavity) (119%, p < 0.05). Reduction of peritoneal mast cell population by chronic treatment of cavities with compound 48/80 did not modify AMA-induced neutrophil migration. The neutrophil chemotaxy assay in vitro shows that the lectin (300 microg/mL) induces neutrophil chemotaxy (368% p < 0.05) compared to RPMI. Finally, injection into peritoneal cavities of supernatants from macrophage cultures obtained after stimulation with AMA (300 microg/mL) enhanced neutrophil migration (110% p < 0.05). Summarizing, our data suggest that A. maculatum agglutinin presents pro-inflammatory activity, inducing neutrophil migration by two ways, one which is independent on resident cells and another one dependent on the presence of these cells.     

Influence of porcine spermadhesins on the susceptibility of boar spermatozoa to high dilution

The effect of heparin-binding and non-heparin-binding spermadhesins on the viability, motility, and mitochondrial activity of boar spermatozoa at the high dilution (300,000 sperm/ml) to which sperm are exposed during the process of sex sorting by flow cytometry was investigated. Incubation of spermatozoa with heparin-binding spermadhesins caused a time- and dose-dependent decrease in the percentage of functional spermatozoa. The percentage of viable spermatozoa incubated at 38 degrees C with heparin-binding spermadhesins diluted in PBS (1 mg/ml) dropped from 75% (0.5 h) to 4% (5 h), whereas the percentage of viable spermatozoa incubated in PBS without proteins (control) decreased from 85% (0.5 h) to 19% (5 h). Addition of non-heparin-binding PSP-I/PSP-II spermadhesin to the PBS resulted in a concentration-dependent increment of the percentage of viable cells (65% after 5-h incubation), with maximum effect at 1.5 mg/ml. The heparin-binding spermadhesins totally suppressed sperm motility and mitochondrial activity after 5 h of incubation. The same parameters of sperm incubated in the presence of 1.5 mg/ml of PSP-I/PSP-II were 50% and 58%, respectively, and the percentages of control sperm displaying motility and mitochondrial activity were 21% and 26%, respectively. Moreover, the viability, motility, and mitochondrial activity all decreased on incubation of spermatozoa with mixtures of PSP-I/PSP-II and heparin-binding spermadhesins as the concentration of the latter increased. We conclude that PSP-I/PSP-II and the heparin-binding spermadhesins exert antagonistic effects on the functionality of highly diluted boar spermatozoa. The finding that PSP-I/PSP-II contributes to maintaining sperm with high viability, motility, and mitochondrial activity for at least 5 h at physiological temperature points to its potential use as an additive for sperm preservation, specifically of highly diluted, flow-sorted spermatozoa for sex preselection.     

The galactose-binding lectin from Vatairea macrocarpa seeds induces in vivo neutrophil migration by indirect mechanism

To explore the pathways by which lectins induce an inflammatory response, the lectin from Vatairea macrocarpa (VML) seeds was used to induce neutrophil migration in rats. The lectin was shown to cause cell migration, with the effect partially blocked when galactose was added to inhibit lectin activity. Neutrophil migration was also reduced when peritoneal cavity of the animals was depleted of their resident cells beforehand, suggesting that neutrophil migration was mediated by an indirect mechanism. Pre-treatment of rats with thioglycollate increased recruitment of neutrophils while depletion of mast cells by the addition of compound 48/80 had little effect on neutrophil infiltration, suggesting the involvement of macrophages in the inflammatory process induced by the lectin. Inhibition of the cyclooxigenase, leukotriene and PAF activities by indomethacin, MK886 and BN50730, respectively, did not modify the pro-inflammatory effect previously observed. However, dexamethasone and thalidomide significantly reduced the population of neutrophils in the peritoneal cavity after lectin injection. The present study suggests that the effects produced by a galactose-binding lectin do not involve lipoxygenase, cyclooxygenase or PAF mediators that are well known to be involved in the inflammatory process. The blocking actions of dexamethasone and thalidimide suggest that as yet unidentified pro-inflammatory mediators are involved.     

Purification and characterization of PSP-I and PSP-II, two major proteins from porcine seminal plasma.

Two major glycoproteins, designated PSP-I and PSP-II, were purified from porcine seminal plasma by ammonium sulfate fractionation, CM-cellulose chromatography, gel filtration on Sephadex G-75 (superfine), and reverse phase high performance liquid chromatography. These two proteins exist in several forms differing mainly in the carbohydrate moiety. The complete amino acid sequence of PSP-I has been determined by automated Edman degradation of peptides generated by proteolytic digestion and cyanogen bromide cleavage. The protein is 109 residues long and has a single glycosylation site at the asparagine residue at position 47. In addition, the N-terminal sequence of PSP-II has also been determined. PSP-I is a unique protein; a sequence homology search using the protein data base did not reveal any significant homology with other proteins. PSP-II shares 50% sequence homology with a family of zona pellucida-binding glycoproteins at the N-terminus.     

Analysis of the stability of the spermadhesin PSP-I/PSP-II heterodimer. Effects of Zn2+ and acidic pH

Spermadhesins are a family of 12-16 kDa proteins with a single CUB domain. PSP-I and PSP-II, the most abundant boar spermadhesins, are present in seminal plasma as a noncovalent heterodimer. Dimerization markedly affects the binding ability of the subunits. Notably, heparin and mannose 6-phosphate binding abilities of PSP-II are abolished, indicating that the corresponding binding sites may be located at (or near) the dimer interface. Pursuing the hypothesis that cryptic binding sites in PSP-I/PSP-II may be exposed in specific physiological environments, we examined the influence of Zn2+ and acidic pH on the heterodimer stability. According to near-UV CD spectra, the core native fold is preserved in the presence of physiological concentrations of Zn2+, a cation unusually abundant in boar seminal plasma. However, the thermostability of the heterodimer decreases significantly, as observed by CD and differential scanning calorimetry. The effect is Zn2+-specific and is reversed by EDTA. Destabilization is also observed at acidic pH. Gel filtration analysis using radioiodinated PSP-I/PSP-II reveals that dissociation of the heterodimer at low (nanomolar) protein concentrations is promoted by both Zn2+ and acidic pH. Although the integrity of the heterodimer in seminal plasma seems to be guaranteed by its high concentration, dissociation may be facilitated in the female genital tract because of dilution of the protein in the intraluminal fluids of the cervix and the uterus, and the acidic fluid of the uterotubal junction. Such a mechanism may be relevant in the regulation of uterine immune reactions.     

Improving the fertilizing ability of sex sorted boar spermatozoa

The sex sorting of spermatozoa by flow cytometry induces damage, since sperm cells are highly diluted, affecting their functionality and fertilizing ability. In this work it was investigated whether the concentration of sex sorted spermatozoa by the sedimentation method, rather than centrifugation, in combination with the presence of the seminal plasma protein PSP-I/PSP-II heterodimer may improve their fertilizing ability. Spermatozoa were sorted by flow cytometry and collected in BTS with 10% of seminal plasma (group C: control) or with 1.5mg/mL of PSP-I/PSP-II heterodimer (group H). Collected spermatozoa from each medium were split into two aliquots. One aliquot of each group was centrifuged (800 x g/5 min) just after sorting and stored 16-18 h at 17 degrees C (groups Cc and Hc) at 6 x 10(6)sperm/mL. The second aliquot was directly stored at 17 degrees C for 16-18 degrees C (group Cs and Hs). After storage the supernatant was discarded and the sedimented pellet adjusted to 6 x 10(6)sperm/mL. Membrane integrity, acrosome status and motility characteristics of spermatozoa from all groups were assessed. Post-weaning pre-ovulatory sows were inseminated by laparoscopy into the oviduct with 0.3 x 10(6) sex sorted spermatozoa to assess their ability to penetrate oocytes in vivo. Putative zygotes were collected 18 h after insemination by washing the oviduct. Penetration and monospermic rates were evaluated. After 16-18 h of storage, centrifuged spermatozoa collected with 10% seminal plasma or 1.5 mg/mL PSP-I/PSP-II heterodimer after sex sorting showed lower (p<0.05) percentages of membrane integrity, motility and fertilization than sedimented spermatozoa. Overall, the presence of 10% seminal plasma or PSP-I/PSP-II heterodimer did not affect the results. However, a positive effect of PSP-I/PSP-II heterodimer (p<0.05) was observed in sedimented spermatozoa. Hence, our results indicate that the sedimentation method in the presence of PSP-I/PSP-II heterodimer improves the in vivo fertilizing ability of sex sorted boar spermatozoa.     

Major proteins of boar seminal plasma as a tool for biotechnological preservation of spermatozoa

Boar seminal plasma is a complex mixture of secretions from the testes, epididymides, and the male accessory reproductive organs which bathe the spermatozoa at ejaculation. The seminal plasma contains factors, mostly proteins, which influence the spermatozoa, the female genital tract, and the ovum. In boars, most of the proteins belong to the spermadhesin family and bind to the sperm surface. Spermadhesins are multifunctional proteins with a wide range of ligand-binding abilities to heparin, phospholipids, protease inhibitors and carbohydrates; the family can be roughly divided into heparin-binding (AQN-1, AQN-3, AWN) and non-heparin-binding spermadhesins (PSP-I/PSP-II heterodimer). These proteins have various effects promoting or inhibiting sperm functions including motility, oviduct binding, zona binding/penetration, and ultimately fertilization. The complexity of the environmental signals that influence these actions have implications for the uses of these proteins in vivo and in vitro, and may lead to uses in improving sperm storage.     

Leukotriene B4 mediates neutrophil migration induced by heme

High concentrations of free heme found during hemolytic events or cell damage leads to inflammation, characterized by neutrophil recruitment and production of reactive oxygen species, through mechanisms not yet elucidated. In this study, we provide evidence that heme-induced neutrophilic inflammation depends on endogenous activity of the macrophage-derived lipid mediator leukotriene B(4) (LTB(4)). In vivo, heme-induced neutrophil recruitment into the peritoneal cavity of mice was attenuated by pretreatment with 5-lipoxygenase (5-LO) inhibitors and leukotriene B(4) receptor 1 (BLT1) receptor antagonists as well as in 5-LO knockout (5-LO(-/-)) mice. Heme administration in vivo increased peritoneal levels of LTB(4) prior to and during neutrophil recruitment. Evidence that LTB(4) was synthesized by resident macrophages, but not mast cells, included the following: 1) immuno-localization of heme-induced LTB(4) was compartmentalized exclusively within lipid bodies of resident macrophages; 2) an increase in the macrophage population enhanced heme-induced neutrophil migration; 3) depletion of resident mast cells did not affect heme-induced LTB(4) production or neutrophil influx; 4) increased levels of LTB(4) were found in heme-stimulated peritoneal cavities displaying increased macrophage numbers; and 5) in vitro, heme was able to activate directly macrophages to synthesize LTB(4). Our findings uncover a crucial role of LTB(4) in neutrophil migration induced by heme and suggest that beneficial therapeutic outcomes could be achieved by targeting the 5-LO pathway in the treatment of inflammation associated with hemolytic processes.     

Neutrophil migration induced by IL-8-activated mast cells is mediated by CINC-1

The aim of this study was to characterize the mediators released by mast cells responsible for IL-8-induced neutrophil migration. It was observed that IL-8 induces a dose-dependent neutrophil migration into peritoneal cavity of rats, but not into air-pouch cavity in which resident mast cells are not present. The transference of peritoneal mast cells to the air-pouch renders this cavity responsive to IL-8. The neutrophil migration induced by IL-8 into the peritoneal cavity was not observed when the peritoneal-resident mast cells were depleted by compound 48/80 or distilled water treatment. Confirming the importance of mast cells, IL-8-stimulated mast cells supernatant induced significant neutrophil migration when injected into peritoneal and air-pouch cavities. The IL-8-induced neutrophil migration was observed not to be dependent on LTB(4), prostaglandins or TNF-alpha, since MK886, indomethacin or thalidomide were unable to block the IL-8-induced neutrophil accumulation 'in vivo' or the release of neutrophil chemotactic factor "in vitro" by IL-8-stimulated mast cells. However, dexamethasone, an inhibitor of the synthesis of pro-inflammatory cytokines, blocked the neutrophil migration induced by IL-8 "in vivo" and also inhibited the release of the neutrophil chemotactic factor by IL-8-stimulated mast cells. Moreover, the incubation of IL-8-stimulated mast cells supernatant with antibody against cytokine-induced neutrophil chemoattractant 1 (CINC-1), but not against TNF-alpha or IL-1beta, inhibited its neutrophil chemotactic activity. Furthermore, we found a significant amount of CINC-1 in this supernatant. In conclusion, we demonstrated that the neutrophil migration induced by IL-8 is dependent on CINC-1 release from mast cells.     

The role of mast cells in thioglycollate-induced inflammation

The possible role of mast cells in the initiation of inflammation was studied in genetically mast cell-deficient mice, WBB6F1-W/Wv. Inflammation was induced by i.p. injection of thioglycollate. The influx of neutrophils was markedly delayed in WBB6F1-W/Wv mice as compared to the WBB6F1-+/+, mice (congeneic controls). At the time (14 h) of maximum influx of neutrophils in WBB6F1-+/+ mice, thioglycollate caused a 3-fold increase in the total cell number in the peritoneal lavage fluid, and the neutrophil count was elevated 14-fold. At the same time point in W/Wv mice, the total cell number in the peritoneal lavage fluid was not increased significantly and the neutrophils were increased only three- to four-fold. Not only was the neutrophil influx in WBB6F1-W/Wv mice delayed, but the length of time during which the neutrophil count was elevated in the peritoneal fluid was significantly shortened. Transfer (i.p.) of mast cells cultured from the bone marrow of congeneic controls corrected the delay in the neutrophil influx. The magnitude of the neutrophil influx in WBB6F1-W/Wv mice was equivalent to that of congeneic controls 9 days after mast cell repletion. Histologic studies were performed to follow the migration and differentiation of mast cells after adoptive transfer into WBB6F1-W/Wv mice. No connective tissue mast cells could be identified on day 9 when the inflammatory reaction was restored. Migration of mast cells into the tissue, as studied in the cecum, progressed steadily. On day 9 after adoptive transfer, the mast cell number was 38% of congeneic controls. Therefore, the increase in thioglycollate-induced neutrophil influx in WBB6F1W/Wv mice after mast cell repletion seemed to be correlated, at least to some extent, with the migration of mast cells into tissues and not with differentiation into connective tissue mast cells. However, a certain maturation and differentiation may have occurred. These results suggest that mast cells play an important role, although they do not seem to be the only cell type responsible for the initiation of inflammation.     

Inhibition of IL-8-induced W3/25+ (CD4+) T lymphocyte recruitment into subcutaneous tissues of rats by selective depletion of in vivo neutrophils with a monoclonal antibody

IL-8 recruits both neutrophils and lymphocytes in vitro and in vivo. To elucidate the mechanisms of lymphocyte recruitment in vivo by IL-8, we examined the role of neutrophil infiltration through selective depletion of circulating neutrophils using a mAb, RP-3. Selective depletion of neutrophils inhibited the IL-8 induced in vivo migration of the W3/25+ (CD4+) T cell subset but did not inhibit that of the MRC-OX8+ (CD8+) subset. These results suggest that CD4+ T cell migration into IL-8-injected s.c. tissues depends on the prior infiltration of neutrophils chemoattracted directly by IL-8.     

The neutrophil migration induced by tumour necrosis factor alpha in mice is unaffected by glucocorticoids

Macrophages harvested from the peritoneal cavities of rats release a neutrophil chemotactic factor (MNCF) in response to stimulation with Gram-negative bacterial lipopolysaccharide (LPS). MNCF has been shown to be active in rats treated with dexamethasone, a glucocorticoid that usually inhibits the neutrophil migration induced in this species by interleukin (IL)-1, tumour necrosis factor alpha (TNFalpha), IL-8, C5a and leukotriene B(4) (LTB(4)). Here we report that macrophages harvested from peritoneal cavities of mice, and stimulated in vitro with LPS, also release a factor that induces neutrophil migration in dexamethasone-treated animals. This chemotactic activity was neutralized by the incubation of the LPS-stimulated macrophage supernatants with a purified polyclonal IgG anti-mouse TNFalpha. In addition, significant amounts of TNF were detected in the supernatants. The neutrophil migration induced by intraperitoneal administration of recombinant murine TNFalpha was also unaffected by pretreatment of the mice with dexamethasone. Moreover, neutrophil migration induced by intraperitoneal injection of LPS was completely blocked by pretreatment of the mice with a monoclonal antibody against murine TNFalpha. In conclusion, our results support the hypothesis that, in contrast to the role of TNF in rats (where it indirectly induces neutrophil migration), in mice, it may be an important mediator in the recruitment of neutrophils to inflammatory sites.     

Helianthus tuberosus agglutinin directly induces neutrophil migration, which can be modulated/inhibited by resident mast cells.

We investigated the effect of Helianthus tuberosus agglutinin (HTA) on neutrophil migration in vivo and in vitro. The role of resident cells in this effect was analyzed. Peritonitis was induced by injecting stimuli into rat (150-200 g) peritoneal cavities, and in vitro neutrophil chemotaxis was performed using a Boyden microchamber. HTA (80, 200, or 500 microg/mL per cavity) induced significant in vivo neutrophil migration (p < 0.05); in vitro assays showed that this lectin also induced neutrophil chemotaxis, an effect inhibited by the incubation of lectin associated with alpha-D(+)-mannose, its specific binding sugar. Depletion of the resident-cell population by peritoneal lavage did not alter HTA-induced neutrophil migration (200 microg/mL per cavity). The opposite strategy, increasing peritoneal macrophages by intraperitoneally injecting rats with thioglycollate, did not enhance the neutrophil migration produced by HTA (200 microg/mL per cavity). In addition, injection of supernatant from HTA-stimulated macrophage culture (300 microg/mL) into rat peritoneal cavities did not induce neutrophil migration. However, reduction of the peritoneal mast-cell population potentiated the neutrophil migration (p < 0.05) induced by HTA (200 microg/mL per cavity). Lectin from H. tuberosus has a direct neutrophil chemotatic effect that is modulated by mast cells.     

Stimulation of leukocyte lysophospholipase activity by noninfectious agents

Mouse peritoneal leukocyte lysophospholipase (LPL) activity was studied to determine whether or not noninfectious agents cause increased enzyme activity and whether neutrophils have LPL activity. In the first study, mice infected with Ascaris suum, a known inducer of LPL activity, were given intraperitoneal injections of proteose peptone, thioglycolate, bovine albumin, paraffin, glycogen, or A. suum whole worm extract (WWE). Cell populations collected from mice injected with A. suum WWE, proteose peptone, thioglycolate, or bovine albumin contained increased numbers of neutrophils and eosinophils. These cell populations had increased LPL activity when treated, in vitro, with either A. suum WWE, zymosan-activated complement, or with the agent they were induced with. However, the LPL activity of the different cell populations did not respond to all treatments in the same way. In a second study, A. suum-infected or noninfected mice were given intraperitoneal injections of paraffin, thioglycolate, glycogen, or A. suum WWE. Enriched cell populations containing either lymphocytes or macrophages, from infected or noninfected mice, did not have increased LPL activity following in vitro stimulation with A. suum WWE, zymosan-activated complement, or with the agent they were induced with. Enriched neutrophil populations from infected or noninfected mice had increased LPL activity following in vitro treatment with A. suum WWE or zymosan-activated complement. Results demonstrate that the LPL activity of peritoneal leukocytes can be induced by noninfectious agents and that neutrophils have increased LPL activity following in vitro stimulation.