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PubMed1980

Concomitant but not causal association between surface charge and inhibition of phagocytosis by cryptococcal polysaccharide.

The mechanism by which capsular polysaccharides inhibit phagocytosis is not clearly understood. We investigated the association between a negative surface charge and inhibition of phagocytosis by the capsular polysaccharide of Cryptococcus neoformans. A two-polymer aqueous-phase system containing phosphate ions was used to assess surface charge. Opsonins such as normal bovine serum and normal human immunoglobulin G reduced the surface charge on non-encapsulated cryptococci and simultaneously enhanced phagocytosis. These same opsonins had no effect on phagocytosis or surface charge of encapsulated cryptococci. F (ab')(2) fragments of normal human immunoglobulin G neither enhanced phagocytosis nor altered the surface charge of non-encapsulated cryptococci. Addition of purified cryptococcal polysaccharide to non-encapsulated cells inhibited phagocytosis of the yeast and induced a strong negative charge at the yeast surface. Chemical modification to reduce the surface charge of either purified cryptococcal polysaccharide or intact encapsulated cryptococci produced a small loss of phagocytosis-inhibiting activity; however, all treated polysaccharide preparations retained a significant ability to inhibit phagocytosis of the yeast. These results indicated that the association between surface charge and inhibition of phagocytosis was largely circumstantial, and presence of a negative surface charge could not account for the powerful antiphagocytic action of cryptococcal polysaccharide.

Cell Membrane↗
PubMed1981

Opsonization of encapsulated Cryptococcus neoformans by specific anticapsular antibody.

Antisera prepared in rabbits against either whole encapsulated cells of Cryptococcus neoformans or purified cryptococcal polysaccharide were opsonic for the encapsulated yeast. The opsonic activity was removed by absorption with whole cryptococci and was inhibited by free polysaccharide. As little as 0.13 microgram of cryptococcal polysaccharide produced a 50% inhibition of opsonization. Various degrees of neutralization by polysaccharides from the four cryptococcal serotypes suggested that the opsonins were type specific. Fractionation of antiserum on Bio-Gel A-5m (Bio-Rad Laboratories) and diethylaminoethyl cellulose showed that the opsonins were antibodies of the immunoglobulin G class. These opsonizing antibodies did not require heat-labile serum components for optimal phagocytosis of the yeast. Inhibition studies using 2-deoxy-D-glucose demonstrated that ingestion of encapsulated cryptococci opsonized with anticapsular antibody was a 2-deoxy-D-glucose-inhibitable process. This result differed from similar studies with non-encapsulated cryptococci which showed that ingestion of non-encapsulated cryptococci opsonized with normal serum was not inhibited by 2-deoxy-D-glucose.

Animals↗
PubMed1982

Interaction of Escherichia coli with different fimbriae and polymorphonuclear leukocytes.

The effects of Escherichia coli strains with various fimbriae on bacteria-polymorphonuclear leukocyte (PMN) interactions were studied. Strains of E. coli were cultivated at 37 degrees C to express and at 18 degrees C to suppress the formation of fimbriae. The presence of fimbriae was confirmed by electron microscopic studies and hemagglutination and salt aggregation tests. Fimbriated E. coli strains were more readily PMN associated than the nonfimbriated strains in the absence of opsonins, confirming the results of previous studies. However, the PMN chemiluminescence (CL) induced by the various strains in the absence of serum opsonins depended on the type of fimbriae they expressed. Strains with type 1 fimbriae expressing mannose-sensitive hemagglutination induced 5 to 15 times more CL than the same strains grown at 18 degrees C, i.e., not expressing this type of fimbriae. For strains showing mannose-resistant hemagglutination, the differences between fimbriated and nonfimbriated variants of the same strains grown at 37 and 18 degrees C, respectively, were less pronounced. Analysis of enterotoxigenic strains expressing colonization factor antigen I (CFA/I) fimbriae showed that these induced only 25 to 33% of the CL induced by the same E. coli strains not expressing CFA/I, whereas enterotoxigenic strains expressing CFA/II fimbriae induced 100 to 200% of the CL induced by the nonfimbriated variants. Although less CL was induced by bacteria with CFA/I fimbriae than by nonfimbriated variants, this situation was reversed when the microorganisms were opsonized. Thus, CFA/I fimbriae, while enhancing adhesion to cells, induce less activation of PMN-killing mechanisms in a serum-free environment. These findings may be relevant for the virulence in certain body sites, since CFA/I fimbriae, while facilitating adhesiveness, may protect the bacteria from PMN killing. Our findings indicate that PMN interactions with fimbriated E. coli in the host defense may be complex. Certain fimbriae may indeed be advantageous to the bacteria, enabling them to interact with PMNs without activating the bactericidal oxidative metabolism.

Adhesiveness↗
PubMed1984

Localization on encapsulated Cryptococcus neoformans of serum components opsonic for phagocytosis by macrophages and neutrophils.

Previous studies have shown that the cryptococcal capsule inhibits phagocytosis of Cryptococcus neoformans by macrophages and neutrophils. In this study, the binding sites of potential serum opsonins in immune and nonimmune sera were determined by immunoelectron microscopy, and the results were compared with the results of phagocytosis of the yeasts by mouse peritoneal macrophages and human neutrophils. Immunoglobulin G (IgG) from normal human serum showed low-density binding at the capsular surface and at sites throughout the capsule. Complement component C3 from normal serum bound heavily at the capsular surface. IgG from rabbit capsular antiserum showed relatively dense deposition at the capsular surface and at sites throughout the capsule. Cells opsonized with heat-inactivated human serum were engulfed poorly by both macrophages and neutrophils, indicating that the low-density deposition of IgG produced by normal serum was not adequate for opsonization. Yeasts opsonized with normal human serum were engulfed in large numbers by neutrophils and to a lesser extent by macrophages, indicating that neutrophils in particular were able to effectively utilize the opsonically active C3 which normal human serum deposited at the capsular surface. Yeasts opsonized with rabbit anticapsular serum were engulfed by both macrophages and neutrophils, indicating that the high density of surface IgG produced by capsular antiserum is an effective opsonin for both cells. These results suggest that the complement-neutrophil system is a possible defense mechanism in the nonimmune host.

Animals↗
PubMed1987

Stimulation of human polymorphonuclear leukocyte oxidative metabolism by type 1 pili from Escherichia coli.

We compared the degree to which Escherichia coli phase variants which do (T1P+ E. coli) or do not (T1P- E. coli) express type 1 pili (T1P) stimulate human polymorphonuclear leukocyte (PMN) oxidative activity. Unopsonized T1P+ E. coli stimulated the release of 0.20 to 0.24 nmol of H2O2 per 10(6) PMN per min and the consumption of 1.4 to 4.0 nmol of O2 per 10(6) PMN per min; no measurable PMN oxidative activity was stimulated by unopsonized T1P- E. coli. In the presence of serum opsonins, T1P+ E. coli stimulated the release of 1.12 to 1.16 nmol of H2O2 per 10(6) PMN per min and the consumption of 5.0 to 6.0 nmol of O2 per 10(6) PMN per min, whereas T1P- E. coli stimulated the release of 0.42 to 0.43 nmol of H2O2 per 10(6) PMN per min and the consumption of 0.6 to 2.0 nmol of O2 per 10(6) PMN per min. Although unaggregated T1P did not stimulate PMN, latex beads coated with T1P (T1P-latex) stimulated alpha-methylmannoside-inhibitable, opsonin-independent PMN oxidative activity. The activity stimulated by either T1P+ E. coli or T1P-latex was susceptible to inhibition by cytochalasin B. Latex particles coated with bovine serum albumin or mannose-resistant pili did not stimulate PMN. These data indicate that T1P+ E. coli stimulate PMN oxidative metabolism more effectively than do T1P- E. coli and that a similar PMN oxidative response follows cellular stimulation by either unopsonized T1P+ or opsonized T1P- E. coli. Furthermore, T1P-latex faithfully mimics the ability of T1P+ E. coli to stimulate PMN oxidative metabolism. Such particles may be useful in further analyses of cellular responses to T1P+ E. coli.

Concanavalin A↗
PubMed1994

Virulence factors determine attachment and ingestion of nonopsonized and opsonized Bordetella pertussis by human monocytes.

In the present study, the role of virulence factors in and the effect of opsonization on the interactions between Bordetella pertussis and human monocytes were investigated. The methods used facilitated the distinction between attachment and ingestion of bacteria by monocytes. Nonopsonized virulent B. pertussis cells attached to monocytes. Nonopsonized B. pertussis mutant strains deficient in filamentous hemagglutinin, fimbriae, or pertactin exhibited a reduced adherence to monocytes compared with that of their respective parental strains. Nonopsonized avirulent B. pertussis cells did not attach to monocytes. These results led to the conclusion that fimbriae and pertactin are involved in the adherence of nonopsonized virulent B. pertussis cells to monocytes and confirm the role of filamentous hemagglutinin in this process. In the absence of opsonins, about 40% of the monocyte-associated virulent B. pertussis cells were ingested. When B. pertussis cells were preopsonized with inactivated normal serum, about 50% of the monocyte-associated virulent B. pertussis cells were phagocytosed and about 80% of the monocyte-associated avirulent B. pertussis cells were ingested. These results indicate that virulence factors inhibit opsonin-mediated ingestion of B. pertussis by monocytes.

Antibodies, Bacterial↗
PubMed1996

Opsonization of Cryptococcus neoformans by human anticryptococcal glucuronoxylomannan antibodies.

Cryptococcal meningitis occurs in 6 to 8% of human immunodeficiency virus-infected individuals. Despite the availability of powerful antifungal agents that are active against Cryptococcus neoformans, these drugs generally fail to cure cryptococcal infections in immunocompromised hosts. Alternative approaches to prevention and therapy of cryptococcosis are urgently needed. Complement promotes phagocytosis of C. neoformans, but human antibodies to cryptococcal capsular polysaccharide have not been shown to function as complement-independent opsonins. The goal of our studies was to characterize the in vitro biological function of human antibodies to glucuronoxylomannan (GXM) from individuals immunized with a GXM-tetanus toxoid (GXM-TT) vaccine. We studied sera from nine vaccinees that manifested good serologic responses to GXM-TT. The results indicate that GXM-TT-elicited antibodies promote phagocytosis of C. neoformans by both murine J774 cells and human peripheral blood mononuclear cells (PBMCs). The two sera with the highest titers of anti-GXM immunoglobulin G2 antibodies were the most opsonic. When PBMC Fc gamma RIIa receptors were blocked, a 75% decrease in phagocytosis occurred following incubation of the PBMCs with C. neoformans opsonized with these sera. Our data indicate that, in the absence of complement, human anti-GXM-TT antibodies are opsonic and that antibodies of the immunoglobulin G2 isotype are effective opsonins.

Adjuvants, Immunologic↗
PubMed2002

Role of Yops and adhesins in resistance of Yersinia enterocolitica to phagocytosis.

Yersinia enterocolitica is a pathogen endowed with two adhesins, Inv and YadA, and with the Ysc type III secretion system, which allows extracellular adherent bacteria to inject Yop effectors into the cytosol of animal target cells. We tested the influence of all of these virulence determinants on opsonic and nonopsonic phagocytosis by PU5-1.8 and J774 mouse macrophages, as well as by human polymorphonuclear leukocytes (PMNs). The adhesins contributed to phagocytosis in the absence of opsonins but not in the presence of opsonins. In agreement with previous results, YadA counteracted opsonization. In every instance, the Ysc-Yop system conferred a significant level of resistance to phagocytosis. Nonopsonized single-mutant bacteria lacking either YopE, -H, -T, or -O were phagocytosed significantly more by J774 cells and by PMNs. Opsonized bacteria were phagocytosed more than nonopsonized bacteria, and mutant bacteria lacking either YopH, -T, or -O were phagocytosed significantly more by J774 cells and by PMNs than were wild-type (WT) bacteria. Opsonized mutants lacking only YopE were phagocytosed significantly more than were WT bacteria by PMNs but not by J774 cells. Thus, YopH, -T, and -O were involved in all of the phagocytic processes studied here but YopE did not play a clear role in guarding against opsonic phagocytosis by J774. Mutants lacking YopP and YopM were, in every instance, as resistant as WT bacteria. Overexpression of YopE, -H, -T, or -O alone did not confer resistance to phagocytosis, although it affected the cytoskeleton. These results show that YopH, YopT, YopO, and, in some instances, YopE act synergistically to increase the resistance of Y. enterocolitica to phagocytosis by macrophages and PMNs.

Actins↗
PubMed1969

Mouse virulence of K(L) antigen-containing strains of Escherichia coli.

The mouse virulence of two K antigen-containing (L variety) strains of Escherichia coli (serotype O2:K1) isolated from human septicemia, and of their variants which lacked K antigen, was studied. The strains containing envelope antigen (K+) were highly virulent when injected intracerebrally or when suspended in mucin and injected intraperitoneally. After intraperitoneal injection of E-107 K+ (but not K-), there was a marked initial growth in the peritoneal cavity followed by bacteremia and infection of all the organs examined. In the mucin-enhanced lethal infection, this growth continued until death of the animal; in the nonlethal infection, growth ceased and the count dropped quickly after approximately 5 hr. Host defenses were depressed greatly by intraperitoneally, but not intravenously, administered mucin. Bacteria were most virulent when injected intraperitoneally. In vitro phagocytosis of the K+ bacteria required opsonins not needed for phagocytosis of the smooth K- variants. Opsonins were found in immunized rabbit and normal mouse sera. Immune rabbit sera contained antibodies with anti-K specificity which were opsonic in vitro and highly protective in vivo when administered passively. There appears to be a lesser anti-O opsonic and protective activity involving one of the strains (E-107 K+), and colonial morphology, agglutination, and absorption tests indicated a low amount of K antigen on this organism. No anti-O opsonic or protective activity could be shown involving the other strain (E-102 K+). When standard serological typing procedures were used, these two strains appeared to be identical serologically, but they differed greatly in sensitivity to immune rabbit serum in phagocytosis experiments in vitro.

Agglutination Tests↗
PubMed1987

Effect of dialysate fluids on phagocytosis and killing by normal neutrophils.

Inadequate host defenses may partly explain the problem of recurrent peritonitis in patients on continuous ambulatory peritoneal dialysis. It has been suggested that these defenses may be adversely affected by the fluids used for dialysis, and so we examined the effects of unused, effluent, and infected peritoneal dialysis fluids on phagocytosis and killing by normal neutrophils. We used a clinical isolate of Staphylococcus epidermidis as the test organism, as this organism is the most commonly cultured in continuous ambulatory peritoneal dialysis peritonitis; we also used a fungal species, Candida guilliermondii. There was no phagocytosis of either organism in unused dialysate because of lack of opsonins and low pH. Phagocytosis in effluent dialysate did not occur because of inadequate opsonin levels and was variable in infected effluents, depending on quantities of immunoglobulins present. Intracellular killing of both test organisms was normal in unused dialysate in the presence of 5% normal serum, but was reduced in effluent and infected dialysates because of factors inhibiting killing by neutrophils. These factors adversely affected the killing of S. epidermidis more than that of C. guilliermondii. These results may explain why peritonitis recurs, particularly peritonitis due to S. epidermidis, because organisms could be sequestered within the neutrophils and thus be protected from antibiotic action. Reinfection of the peritoneal cavity would then take place following neutrophil breakdown, causing a clinical relapse.

Candida↗
PubMed1981

Inhibition by sugars of opsonization of Staphylococcus aureus in fetal calf serum.

Phagocytosis of Staphylococcus aureus by human peripheral polymorphonuclear leucocytes in vitro in the presence of fetal calf serum was inhibited by D-galactose, N-acetyl-D-glucosamine and asialofetuin but not by fetuin. Absorption of opsonin in the serum with the bacteria, inhibition of the absorption by sugars and the effect of glycosidase treatment of the bacteria on phagocytosis showed that terminal structures of polysaccharides on the surface of bacteria play an important role in binding of opsonin to the target.

Absorption↗
PubMed1997

Nonimmune phagocytosis of liposomes by rat alveolar macrophages is enhanced by vitronectin and is vitronectin-receptor mediated.

Pulmonary alveolar macrophages (AMs) engulf diverse materials. The mechanisms allowing AMs to recognize, bind, and phagocytose these materials are poorly understood. To test the hypothesis that the adhesive glycoprotein vitronectin (Vn) acts as a nonimmune opsonin, we studied AM-Vn binding and AM phagocytosis of fluorescent liposomes under the following conditions: (1) pretreatment of AMs with Vn, followed by incubation of AMs with liposomes containing increased amounts of Vn; (2) inhibition of phagocytosis by gly-arg-gly-asp-ser (RGD) and gly-pen-gly-arg-gly-asp-ser-pro-cys-ala (GPen); and (3) antibody blockade of the alpha(v)beta3 vitronectin receptor (VnR). Pretreatment of AMs with 0.1, 1, and 2 microM Vn progressively enhanced AM-Vn binding from 23,622 +/- 3,328 cpm to 40,847 +/- 6,530 cpm, 57,149 +/- 2,789 cpm, and 124,852 +/- 42,930 cpm, respectively (P < 0.05). AM pretreatment also increased phagocytosis of Vn-enriched liposomes, but not empty liposomes (20.7 +/- 0.4 liposomes/cell versus 11.5 +/- 0.5 liposomes/cell, P < 0.05). Moreover, increased concentrations of Vn in liposomes progressively increased phagocytic activity (3.7 +/- 0.3, 6.5 +/- 0.2, 11.5 +/- 0.5, and 16.5 +/- 0.6 liposomes/cell with 0.01, 0.1, and 1 microM Vn, respectively, P < 0.05). RGD inhibited Vn-enhanced phagocytosis (8.1 +/- 0.4 liposomes/cell to 3.4 +/- 0.2, 2.4 +/- 0.4, and 2.2 +/- 0.2 liposomes/cell with 0.02, 0.2, and 2 mM RGD, respectively, P < 0.05), as did GPen (4.7 +/- 0.8 liposomes/cell versus control = 10.9 +/- 1.5 liposomes/cell, P < 0.05) and anti-VnR antibody (3.3 +/- 0.4 liposomes/cell versus control = 8.9 +/- 1.7 liposomes/cell, P < 0.05). We conclude that AMs employ Vn as a nonimmune opsonin to enhance the efficiency of phagocytosis.

Animals↗
PubMed1970

Leukocytic function in hypogammaglobulinemia.

The phagocytic, bactericidal, and metabolic capabilities of circulating blood leukocytes from three adults (two males, one female) with hypogammaglobulinemia and recurrent pneumonia, chronic sinusitis, and intestinal giardiasis were studied. These functions were found to be normal when leukocytes from the patients were incubated in media containing normal human serum. Phagocytosis of Staphylococcus albus and polystyrene balls by both patient and normal leukocytes was diminished when the cells were incubated in hypogammaglobulinemic plasma. A similar defect in opsonization by patient plasma was also noted for pneumococci, Escherichia coli and variably with Staphylococcus aureus. Both patient and normal sera had equivalent levels of heat-labile S. albus opsonins; normal serum, however, contained heat-stable S. albus-specific absorbable opsonins in significantly greater quantities to account for its superior opsonic capacity. The addition of commercial gamma globulin or purified IgG to hypogammaglobulinemic sera restored full S. albus opsonic activity. The relevancy of these observations to the impaired host defenses in these patients will be discussed.

Agammaglobulinemia↗
PubMed1989

Nonopsonic antibodies in cystic fibrosis. Pseudomonas aeruginosa lipopolysaccharide-specific immunoglobulin G antibodies from infected patient sera inhibit neutrophil oxidative responses.

Antibody opsonins from cystic fibrosis (CF) patients were investigated using nonmucoid and mucoid lipopolysaccharide (LPS) immunotype 1 Pseudomonas aeruginosa as bacterial ligands and PMN phagocytes. CF sera were compared to normal sera, polyvalent PA LPS hyperimmune globulin, and isotype switch variant monoclonal antibodies (MAbs) specific for type 1 PA LPS. Sera from PA-infected CF patients (CF PA+) had elevated levels of PA LPS and alginate IgG antibodies and promoted significantly greater antibody-dependent PMN chemiluminescence responses than sera from uninfected CF patients (CF PA-) or normal human sera (NHS). After adjustment for autologous IgG PA LPS antibody content, however, CF PA+ sera had less antibody-dependent opsonic activity than sera from CF PA- patients (P less than 0.025) or NHS (P less than 0.0025), suggesting qualitative opsonic defects of IgG PA LPS antibodies in CF PA+ sera. Antigen-specific immunoprecipitation of PA LPS antibodies enhanced opsonization by 40% of CF PA+ sera while uniformly reducing that from CF PA- sera (P less than 0.01), indicating LPS-specific nonopsonic antibodies in some CF PA+ sera. Alginate antibodies were not critical opsonins in most uninfected CF patient sera. PA LPS IgG antibodies isolated by immunoaffinity chromatography from NHS, hyperimmune globulin, and CF PA- sources were opsonic and had greater activity at equal antigen-binding concentration than identical antibodies isolated from infected CF patients (P less than 0.01-0.05); the majority of isolates from CF PA+ sera did not promote PMN oxidative responses above nonopsonic baseline. A potential isotypic basis for these findings was supported by differences in PMN responses to PA opsonized with MAbs of identical specificity but differing isotypes. PA LPS-specific IgG antibodies inhibiting PMN oxidative responses in infected patient sera demonstrate antigen-specific immunomodulation of host responses by chronic bacterial parasitism in CF, which may play a role in the pathophysiology of lung disease.

Antibodies, Bacterial↗
PubMed1995

Activation of the neutrophil bactericidal activity for nontypable Haemophilus influenzae by tumor necrosis factor and lymphotoxin.

Previous studies have suggested that, in vivo, activated T lymphocytes and neutrophils are important in immunity to nontypable Haemophilus influenzae. We now extend this work by showing that neutrophils pretreated with products of activated T lymphocytes or activated macrophages show significantly enhanced killing of nontypable H. influenzae. Lymphotoxin, a product of activated T lymphocytes, significantly enhanced the neutrophil-mediated killing of nontypable H. influenzae, and tumor necrosis factor, produced by activated T lymphocytes as well as macrophages stimulated by activated T lymphocytes, also significantly increased the bactericidal activity of neutrophils. These cytokine-induced effects were seen with short pretreatment times of neutrophils and were maximal by 30 min. The killing of H. influenzae by neutrophils required the presence of heat-labile opsonins. In the absence of these opsonins, both tumor necrosis factor and lymphotoxin were unable to promote the killing of the bacteria by neutrophils. Furthermore, the results showed that tumor necrosis factor-primed neutrophils displayed significantly increased expression of CR3 and CR4 that was associated with increased phagocytosis of complement-opsonized nontypable H. influenzae. These cytokines may play an important role in immunity toward nontypable H. influenzae by stimulating neutrophil bactericidal activity.

CD11 Antigens↗
PubMed1991

Stimulation of erythrophagocytosis in mouse peritoneal macrophages by chondroitin sulfates: correlation with effect of phorbol esters.

Resident macrophages which were harvested from the mouse peritoneal cavity showed the attachment activity to opsonized erythrocytes (OE) without the treatment of chondroitin sulfates (CSA) or phorbol esters. Phorbol ester (phorbol 12-myristate 13-acetate or phorbol 12,13-diacetate) rapidly activated an opsonin-dependent erythrophagocytosis in resident macrophages, whereas CSA slowly activated it in vivo and in vitro. An additive effect of phorbol esters was observed in macrophages which were cultured with CSA in vitro or stimulated by the intraperitoneal injection of CSA for 1 or 2 day(s). In the case of macrophages stimulated by the intraperitoneal injection of CSA for 3 or 4 days the erythrophagocytic activity was at very high level and the additive effect of phorbol esters vanished. These results indicate that CSA plays a role in the induction of opsonin-dependent ingestion activity of resident macrophages.

Animals↗
PubMed2002

The identification and properties of chitin-binding protein b01 (CBPb01).

Bovine serum contains N-acetyl-D-glucosamine (GlcNAc)-sensitive opsonin inhibitory factors. In the present study, a major component of chitin-binding protein (chitin-binding protein b01, CBPb01) was purified from bovine serum, and identified CBPb01 as bovine IgM by its subunit structure, antigenic properties, and partial sequences. The results of a lectin-binding assay showed that the heavy chain of CBPb01 had a GlcNAc structure, but the commercial IgM did not. It is possible that CBPb01 interconnects through its GlcNAc structure, subsequently forming complexes. We also demonstrated that CBPb01 had opsonin-inhibitory activity, and that this activity was dependent on the binding of CBPb01 to GlcNAc on the zymosan surface. These findings indicate the presence of a kind of IgM that recognizes GlcNAc structure in the regulation of opsonization.

Acetylglucosamine↗
PubMed1987

Mechanisms of non-opsonized zymosan-induced and luminol-enhanced chemiluminescence in whole blood and isolated phagocytes.

A luminol-dependent non-opsonized zymosan-induced chemiluminescence method for phagocytes in small quantities of whole blood (40 microliters; final dilution: 1:14) is described. It was characterized with reference to cellular and humoral components, and also applied to isolated neutrophils, eosinophils and monocytes. Normal values for whole blood chemiluminescence and for neutrophils, eosinophils and monocytes are presented. From the chemiluminescence characteristic of distinct phagocytes and their frequency distribution pattern in whole blood, it is concluded that whole blood chemiluminescence has its source predominantly in neutrophils. The question as to the origin of chemiluminescence in phagocytes of whole blood and isolated neutrophils is investigated. The results support the importance of the myeloperoxidase-H2O2-halide system, but also go beyond this. The release of arachidonic acid by phospholipase A2 and of diacylglycerol and inositol trisphosphate by phospholipase C, the metabolism of arachidonic acid by the cyclooxygenase and lipoxygenase pathway, the activation of membrane NADPH oxidase by diacylglycerol and the calcium mobilisation by inositol trisphosphate are necessary for the chemiluminescence reaction. Inhibition of either mechanism suppresses the chemiluminescence response. The interaction of non-opsonized zymosan with plasma opsonins, phagocyte Fc- and complement receptors, respectively, for the initiation of chemiluminescence, was investigated. Non-opsonized zymosan initiates a chemiluminescence response in blood phagocytes in the absence of opsonin from the interaction of the zymosan polysaccharide component glucan with the complement receptor type 3. In the presence of plasma this receptor type also mediates the major chemiluminescence response brought about by the zymosan-coated cleavage products of complement fraction three, iC3b and to a minor degree C3b, while immunoglobulin G-coated zymosan interaction with the Fc-receptor is in this case of minor importance.

Eosinophils↗