Antimicrobial binding of a radiolabeled cationic neutrophil granule protein

A 57,000-dalton protein (CAP57) purified from human polymorphonuclear leukocytes has antimicrobial activity against a number of gram-negative bacteria. We developed a procedure using solid-phase Iodo-gen to radiolabel CAP57 without destroying its antibacterial activity. Iodinated and native CAP57 were electrophoretically identical. Autoradiographs of sodium dodecyl sulfate-polyacrylamide gels revealed greater than 95% of the 125I in a single heavy band in the 57,000-molecular-weight region. The quantity of [125I]CAP57 bound to bacterial test strains was directly proportional to the sensitivity to CAP57.

cDNA cloning of human myeloperoxidase: decrease in myeloperoxidase mRNA upon induction of HL-60 cells

Myeloperoxidase (MPO), the most abundant neutrophil protein, is a bacteriocidal component of the primary granules and a critical marker in distinguishing acute myelogenous leukemia from acute lymphoid leukemia. A cDNA clone for human MPO was isolated by immunologic screening of human hematopoietic lambda gt11 expression vector libraries with specific anti-MPO antibody. The identity of the cDNA clone was confirmed by finding that epitope-selected antibody against this clone recognizes purified MPO and MPO in human promyelocytic (HL-60) cell lysates by immunoblot analysis, and that hybrid selection of HL-60 mRNA with this cDNA clone and translation in vitro results in the synthesis of an 80-kDa protein recognized by the anti-MPO antiserum. RNA blot analysis with this MPO cDNA clone detects hybridization to two polyadenylylated transcripts of approximately 3.6 and approximately 2.9 kilobases in HL-60 cells. No hybridization is detected to human placenta mRNA. Upon induction of HL-60 cells to differentiate by incubation for 4 days with dimethyl sulfoxide, a drastic decrease in the hybridization intensity of these two bands is seen. This is consistent with previous data suggesting a decrease in MPO synthesis upon such induction of these cells. The MPO cDNA should be useful for further molecular and genetic characterization of MPO and its expression and biosynthesis in normal and leukemic granulocytic differentiation.

Late intraphagosomal hydrogen ion concentration favors the in vitro antimicrobial capacity of a 37-kilodalton cationic granule protein of human neutrophil granulocytes

We described previously (W.M. Shafer, L.E. Martin, and J.K. Spitznagel, Infect. Immun. 45:29-35, 1984) the presence of a 37-kilodalton cationic antimicrobial protein (37K CAP) in extracts of granules prepared from human polymorphonuclear granulocytes (PMN). In this investigation, we prepared 37K CAP from PMN granule extracts by sequential ion-exchange and molecular-sieve chromatography and examined its antimicrobial activity against a number of gram-negative and gram-positive bacteria. At concentrations of 5 micrograms/ml or lower, 37K CAP exerted selective antimicrobial activity against gram-negative bacteria. These bacteria included Acinetobacter lwoffii, Escherichia coli, Neisseria gonorrhoeae, Pseudomonas aeruginosa, Pseudomonas cepacia, Salmonella typhi, Salmonella typhimurium, and Shigella sonnei. However, at 5 micrograms of 37K CAP per ml, Proteus mirabilis, Proteus vulgaris, and Serratia marcescens resisted this antimicrobial activity. The bactericidal activity of 37K CAP was greatest in acidic (pH 5.5) as opposed to alkaline (pH 7.5) media. The level of S. typhimurium resistance to 37K CAP correlated with the presence of O antigen in the lipopolysaccharide. In the absence of O antigen repeat units, resistance was proportional to the length of the core oligosaccharide. These results suggest that 37K CAP may contribute significantly to the ability of PMN to kill gram-negative bacteria by nonoxidative means, particularly as the maturing phagolysosome becomes acidified.

Modulation of complement fixation and the phlogistic capacity of group A, B, and D streptococci by human lysozyme acting on their cell walls

Streptococci and streptococcal cell wall fragments induce arthritis in rats, with the severity and duration depending on the capacity of the cells or cell fragments to resist degradation by tissue enzymes. Their phlogogenic effects are apparently related to their ability to activate the alternate complement pathway (ACP). The in vitro activation of the ACP by lysozyme-treated cells and cell walls of group A, B, and D streptococci suggests that both rat and human lysozyme can modulate this activity, i.e., increasing it, decreasing it, or doing both in that order. The effects of the lysozymes also correlated with the degree to which they can unmask the aminosugar-reducing groups detectable in a given amount of cell wall, which suggests that partial depolymerization of the cell wall is critical for ACP activation. The effects of mutanolysin and C phage lysin on ACP activation were found to be correlated with their action on streptococcal cell walls. Neuraminidase had relatively little effect on ACP activation by most streptococcal strains tested. We conclude that the participation of tissue enzymes, including but not necessarily limited to lysozyme, is an important determinant for the clinical arthritis induced by group A, B, or D streptococci. Experimental arthritis induced in rats with whole (or disrupted) streptococci may depend both on the capacities of the cell walls to activate the ACP and on the capacities of the host tissue enzymes to modulate this activation. Great severity and long durations of the disease were determined by the capacity of the enzymes to degrade cell wall antigens to a degree sufficient to ensure efficient activation of the ACP without completely degrading the material so that it no longer activates complement. In this model, the limited resistance of group B peptidoglycan to lysozyme was a critical pathogenic factor.

Neisseria gonorrhoeae survive intraleukocytic oxygen-independent antimicrobial capacities of anaerobic and aerobic granulocytes in the presence of pyocin lethal for extracellular gonococci

The resistance of a piliated, transparent variant of Neisseria gonorrhoeae FA19 to intraleukocytic killing by human polymorphonuclear neutrophils (PMN) was examined. In both aerobic and anaerobic PMN monolayers, approximately 2% of the intracellular gonococci survived for as long as 165 min. Anaerobic PMN were as effective as aerobic PMN in the intracellular killing of gonococci. Hence, O2-independent antimicrobial systems of PMN performed a significant role in the intraleukocytic killing of gonococci were intracellular was supported by the elimination of extracellular bacteria by the addition of pyocin 103 and confirmed by the fluorescent antibody staining of intact gonococci after the PMN were permeabilized to antibody with a Formalin-acetone treatment of PMN monolayers. Our data indicate that while the majority of ingested gonococci are killed by O2-independent antimicrobial systems, a small number (about 2%), survive even when care is taken to eliminate extracellular bacteria.

Neutrophil killing of bacteria by oxygen-independent mechanisms: a historical summary

The historical development of the concept of neutrophil killing of bacteria by oxygen-independent mechanisms is traced. The role of oxygen-independent microbicidal mechanisms in relationship to neutrophil management of microbes is critically evaluated. In the ultrastructural sense, oxygen-independent killing of bacteria requires the deposition of a bactericidal component (granule proteins) or the establishment of a hostile, non-physiologic environment in the phagolysosome. Accordingly, this review is concerned with the identification and cellular location of cationic proteins that participate in nonoxidative killing of gram-negative bacteria by human polymorphonucleur neutrophil granulocytes. Studies reviewed support the hypothesis that oxygen-independent mechanisms function in vivo and are important in host defense against infection. The chemistry of antimicrobial proteins, the biologically active site of each protein, and the mechanism by which the proteins trigger bacterial death all need to be determined at the molecular level.

Toxicity of group B Streptococcus agalactiae in adult rats

Several strains of group B Streptococcus agalactiae were found to be lethal for young adult rats. When bacteria were heat killed and then injected intraperitoneally into rats, rapid death (14 to 18 h) of the rats occurred, characterized by labored breathing, hemolyzed serum, hemoglobinuria, and subungual hemorrhages. Sections of tissues from these rats failed to reveal the cause of death. Rats injected with toxic or nontoxic strains of group B S. agalactiae had reduced numbers of circulating leukocytes and low serum C3 levels in comparison with those in control rats. The toxic strains of group B S. agalactiae induced dramatic decreases in platelet numbers, and in plasma fibrinogen levels as well, suggesting that the toxicity was due to disruption of the coagulation system. Rapid death in the absence of infection suggests that group B S. agalactiae may have a cell-associated toxin that induces these changes. Such a toxin may be a contributory factor in the high mortality rate associated with group B streptococcal infections of the human neonate.

Anaerobiosis increases resistance of Neisseria gonorrhoeae to O2-independent antimicrobial proteins from human polymorphonuclear granulocytes

We investigated the in vitro resistance of Neisseria gonorrhoeae FA19 to the O2-independent antimicrobial systems of human polymorphonuclear leukocytes. Acid extracts of polymorphonuclear leukocyte granules (crude granule extracts) and a purified granule protein (57 kilodaltons) were, at low concentrations, bactericidal for gonococci under aerobic conditions that permitted growth. However, they were less effective under anaerobic conditions that imposed bacteriostasis. We found that adding sodium nitrite to reduced growth media permitted the growth of strain FA19 in an anaerobic environment. Under these conditions with nitrite, anaerobic cultures of strain FA19 were no more resistant to the crude granule extract and the 57-kilodalton protein than aerobic cultures. In contrast, Salmonella typhimurium SL-1004, a facultative anaerobe, was readily killed by both the crude granule extract and the 57-kilodalton antimicrobial protein regardless of the presence or absence of free molecular oxygen. This is the first demonstration that an isolated antimicrobial protein from polymorphonuclear leukocyte granules is active against bacteria under anaerobic conditions. Our results also indicated that the efficacy of human polymorphonuclear leukocyte O2-independent killing of N. gonorrhoeae may, in part, be inhibited by bacteriostatic conditions imposed by hypoxia.

Peritoneal macrophages of pathogen-free rats but not of conventional rats secrete elastolytic activity

Elicited peritoneal macrophages from Sprague-Dawley rats conventionally bred and housed failed, as we have reported, to produce detectable elastolytic activity in culture. They did produce lysozyme and plasminogen activator. We now show that in contrast to these cells, macrophages from pathogen-free, barrier-sustained rats produced readily demonstrable elastolytic activity. Rats raised pathogen-free and subsequently housed conventionally for 2-4 wk appeared to lose the capacity to afford macrophages producing elastase. At the same time they acquired infections with several rat pathogens including Spironucleus muris, Kilham rat virus, sialodacryoadinitis virus, and mycoplasma pulmonis. The acquisition by the rats of one or more of these infections, conditions conducive to infection, or both factors may have suppressed their capacity to yield elastolytic activity.

Cationic antimicrobial proteins isolated from human neutrophil granulocytes in the presence of diisopropyl fluorophosphate

Acid (0.2 M sodium acetate, pH 4.0) extracts of granules recovered from disrupted human polymorphonuclear granulocytes (PMNs) exhibited in vitro antimicrobial activity against Salmonella typhimurium. To minimize proteolytic destruction or modification of antimicrobial proteins derived from these granules, we pretreated the PMNs with the serine protease inhibitor diisopropyl fluorophosphate. Fractionation of such extracts by carboxymethyl Sephadex and Sephadex G-75 chromatography resulted in the recovery of at least two antimicrobial, cationic proteins. These proteins differed substantially in antimicrobial activity, amino acid composition, and molecular weight (Mr, 37,000 and 57,000). As we have shown before (Shafer et al., Infect. Immun. 43:834-858), with unfractionated proteins, these two proteins exhibited diminished activity against a polymyxin B-resistant (PBr) mutant of S. typhimurium compared with their activity against the isogenic parental polymyxin B-sensitive (PBs) strain. Expression of the relevant mutation (prmA) in the PBr mutant decreases the electronegativity of lipid A, owing to increased 4-amino-4-deoxy-L-arabinosylation at the 4' phosphate residue (Vaara et al., FEBS Lett. 129:145-149). The data suggest that at least two different cationic proteins account for the antimicrobial capacity of extracts from human PMN granules. Moreover, the availability of anionic charges in the outer membrane of S. typhimurium due to free lipid A phosphates apparently dictates phenotypic levels of resistance to both of the cationic proteins extracted from human PMN granules.

Lipid A and resistance of Salmonella typhimurium to antimicrobial granule proteins of human neutrophil granulocytes

Granule extracts from human polymorphonuclear leukocytes were prepared and fractionated by chromatography on Sephadex G75-SF. One fraction exhibited potent antimicrobial activity against an Rd1 lipopolysaccharide (LPS) mutant of Salmonella typhimurium. Susceptibility of the mutant to antimicrobial activity appeared to be due to binding of granule proteins to lipid A because isolated native LPS succeeded in blocking the antimicrobial activity of granule extracts whereas base-hydrolyzed LPS failed to do so. Centrifugation of control and base-hydrolyzed LPS-protein mixtures in cesium chloride gradients suggested that only control LPS formed complexes with antimicrobial proteins. Further evidence that bactericidal proteins from polymorphonuclear leukocyte granules interact with lipid A was that sublethal concentrations of polymyxin B (an antibiotic known to bind to lipid A) rendered target bacteria phenotypically resistant to granule proteins. Moreover, a mutant of S. typhimurium which synthesized a lipid A with decreased electronegativity due to increased 4-amino-4-deoxy-L-arabinosylation at the 4'-phosphate exhibited increased resistance to both polymyxin B and granule proteins. These results suggest that polymyxin B and antimicrobial proteins derived from polymorphonuclear leukocyte granules interact with lipid A in an analogous manner.

Nonoxidative antimicrobial reactions of leukocytes

Increasingly abundant evidence supports the hypothesis that PMNs and perhaps alveolar macrophages have antimicrobial mechanisms independent of the presences of molecular oxygen for effective action against an array of bacteria and against some fungi. Eosinophils have mechanisms toxic for schistosomula and Trichinella larvae. In all instances the antimicrobial substances isolated have been cationic proteins and, in PMNs, associated with the azurophil cytoplasmic granules of the PMNs. Several of these substances have thus far demonstrated no enzymic function. Two of these substances are serine proteases but in one, chymotrypsin-like protein, the antimicrobial action depends on the cationic properties of the protein and is independent of the proteolytic action of the substance. In most instances, these proteins are cationic due to relatively large proportions of arginine. In two instances, a large proportion of lysine is present. All have high proportions (about 50%) of hydrophobic amino acid. Such proteins occur in the PMNs of man, rabbit, guinea pig, rat, cow, and chicken. The present view is that they are most active against gram-negative bacteria. At least two of them-37-kd and 57-kd proteins (Shafer and Spitznagel, 1983)-act on S. typhimurium in a manner analogous to that of polymyxin B through binding to lipid A. Currently available results shows that anaerobic PMNs have substantial antimicrobial capacity. Whether this capacity is due to the O2-independent mechanisms discussed in this chapter remains to be established with greater certainty.

An enzyme-linked immunoassay (ELISA) for measurement of lactoferrin

An enzyme-linked immunosorbent assay has been developed for quantitation of lactoferrin (LF) in body fluids. An indirect double-sandwich method was used which allows a sensitivity of 3 ng LF/ml in samples of polymorphonuclear cell lysates and serum. Mean LF content of serum was 0.307 +/- 0.066 micrograms/ml (n = 18). Mean LF content of polymorphonuclear cells was 4.90 +/- 1.48 micrograms/10(6) PMN. Concentrations of LF were similar in serum and in plasma of EDTA anticoagulated blood. Advantages of this method include its rapidity, and radioactivity is not required.

Microbial interactions with neutrophils

Bacterial pathogenesis is heavily dependent on the capacities of microbial cells to avoid activating or to resist antimicrobial mediators of neutrophil polymorphonuclear granulocytes, the first line of phagocytic defense against infection. These capacities can but be understood in terms of the cell biology of neutrophils. The relevant microbial mechanism largely reside in the biochemical structures of their cell surfaces and their secretions. These factors are reviewed, and the importance of biochemical genetic analysis in seeking new solutions to old and new problems is stressed.

Differential distribution of distinct forms of myeloperoxidase in different azurophilic granule subpopulations from human neutrophils

Myeloperoxidase (MPO), a characteristic enzyme of human polymorphonuclear neutrophils (PMN), is localized in specialized lysosomal or azurophilic granules, and can be resolved into three distinct forms (I, II, III) by ion-exchange chromatography. Granules were isolated from single donor PMN and fractionated with centrifugation into two different azurophilic subpopulations (high and low density) by banding in a continuous sucrose density gradient. Ion-exchange chromatography of granule extracts indicated that the lower density granules contained mainly MPO forms II and III while the higher density granules appeared to contain all three forms, but in much reduced amounts. Sodium dodecylsulfate polyacrylamide gel electrophoresis showed that, the mobilities of the heavy subunits of MPO appeared to be inversely related to the density of the granule population from which they were extracted. These observations suggest that the different forms of MPO may have distinct functional roles and/or are a possible reflection of maturational differences among the granule subpopulations.

Rat arthritis due to whole group B streptococci. Clinical and histopathologic features compared with groups A and D

Heat-killed streptococci of Groups A, B, and D injected intraperitoneally into Sprague-Dawley rats induced arthritis. The histopathologic features of the arthritis were those of erosive synovitis. Early acute lesions were associated with deposits of streptococcal antigens. The serogroups and the physical state of the streptococci determined the incidence, the time of onset, the duration, and the severity of the disease, the severity being a blend of degree of inflammation, tendency to relapse, and occurrence of ankylosis. Whole Group A usually failed to induce arthritis. Group A disrupted with sonication regularly induced arthritis after a 24-hour latent period. The disease lasted over 60 days and caused ankylosis. Whole Group B regularly induced arthritis but only after a latent period of 6-8 days. The disease lasted over 40 days and caused ankylosed joints. With sonicated Group B a similar disease was induced, except that, as with sonicated Group A, the latent period was 24 hours. Whole Group D induced disease after a latent period of 48 hours. The arthritis lasted only 2 weeks and was transient. In contrast to its effects on Group A and B cocci, sonication of Group D abrogated its capacity to induce arthritis. It is postulated that for whole streptococci, in contrast to sonicated streptococci, arthritogenicity depends on the sensitivity of the cocci to initial processing in vivo. Processing may be partial digestion by enzymes of phagocytes. Cocci such as those of Group A that are insensitive to processing, injected whole, tend not to cause arthritis, but when they do cause disease, it is chronic. A coccus, such as one of Group D, that is very sensitive to processing produces a transient arthritis after a short latent period, while a coccus of intermediate sensitivity, such as one of Group B, induces disease only after a substantial latent period, and the disease is severe and chronic. The nature of processing remains to be determined.

Outer membrane mutants of Salmonella typhimurium LT2 have lipopolysaccharide-dependent resistance to the bactericidal activity of anaerobic human neutrophils

The capacity of neutrophil polymorphonuclear granulocytes (PMNs) to phagocytize bacteria under anaerobic as well as aerobic conditions afforded the opportunity to compare the bactericidal activities of oxygen-independent and oxygen-dependent antimicrobial mechanisms in human PMNs challenged with Salmonella typhimurium LT2 and its lipopolysaccharide mutants (outer membrane mutants). Anaerobic human PMNs challenged with either opsonized LT2 or serum-treated zymosan failed to produce detectable superoxide anion (O2-) or to reduce nitroblue tetrazolium, although aerobic PMNs readily produced O2- in response to such challenge. Anaerobic PMNs killed these bacteria in an ordered fashion that appeared to be dependent on their lipopolysaccharide chemotype. As the carbohydrate content of the mutant lipopolysaccharide decreased, the bacteria became less resistant to the oxygen-independent bactericidal activity. The results resembled the ordered resistance to oxygen-independent killing observed with LT2 and its mutants in PMN-free systems with PMN granule proteins. Studies on the kinetics of killing showed these to be less rapid in anaerobic as compared with aerobic conditions. Opsonization increased the rate of phagocytosis, but such factors as opsonization and the rate of phagocytosis did not appear to affect intraleukocytic bactericidal capacity in that the resultant proportion of bacteria remaining viable after ingestion was similar regardless of which serum was used (normal serum, C6-deficient serum, C8-deficient serum, or no serum at all). The results are consistent with an active and substantial participation by oxygen-independent systems in the antimicrobial effects of neutrophils.

Characterization of rat polymorphonuclear leukocyte subcellular granules

The bactericidal subcellular granules of rat peritoneal neutrophils were studied to determine selected physical and biochemical characteristics. Isopycnic centrifugation of these granules resolved them into three subpopulations: specific granules (buoyant density = 1.176) as well as light and heavy azurophil granules (buoyant density = 1.20 and 1.22, respectively). These buoyant densities corresponded closely to those of similarly isolated human granules. Specific granules of rat peritoneal neutrophil contained 68 per cent of the sedimentable alkaline phosphatase activity and part of the lysozyme of the whole rat peritoneal neutrophil. The light azurophil granules contained the remainder of the lysozyme, as well as a substantial portion of the beta-glucuronidase activity. Peroxidase was detected in both light and heavy azurophil granules, as was neutral protease. Morphologically, the rat specific granules were round or slightly ovoid organelles (0.10 to 0.13 micrometer in diameter). The azurophil granules were larger (0.3 micrometer) ellipsoid as well as round in shape, and stained strongly for peroxidase. These granules were significantly smaller than the crystal-containing granules of eosinophils.

Selective modification of rat peritoneal macrophage lysosomal hydrolases by inflammatory stimuli

Lysosomal acid hydrolases were surveyed in elicited and non-elicited rat peritoneal macrophages to determine the types of enzymes present and optimal assay conditions. Adherent peritoneal cells (primarily macrophages) were cultured 24 hours prior to use. Intracellular distribution of enzymes was determined by differential centrifugation of whole cell homogenates into nuclear, cytoplasmic, and lysosomal fractions. The acid glycosidase, acid phosphatase, acid protease, and lysozyme were largely sedimentable in the lysosomal fraction. Much enzyme activity was latent, being activated by addition of Triton X-100. Chymotrypsin-like protease activity in cell fractions was apparently due to low level mast cell contamination. Elicited macrophages had elevated total cell protein as compared to non-elicited cells, but changes in intracellular enzyme levels were selective depending on the enzyme and the stimulus used to elicit macrophages. Thioglycollate-elicited cells showed elevations of most acid hydrolases compared to non-elicited cells, whereas enzyme levels in zymosan-elicited cells were similar to those in non-elicited cells. All elicited cells showed marked decreases in total cellular alpha-D-mannosidase and alpha-L-fucosidase compared to non-elicited cells. Intracellular lysozyme levels also varied between different rat strains. Cultured macrophages exhibited increasing intracellular levels and extracellular secretion of acid hydrolases, especially extracellular lysozyme (10-25 mug/10(6) cells/day), over 72 hours. No significant intra- or extracellular elastinolytic activity was detected.

Gonococci with mutations to low-level penicillin resistance exhibit increased sensitivity to the oxygen-independent bactericidal activity of human polymorphonuclear leukocyte granule extracts

Gonococci which cause disseminated gonococcal infection are nearly always highly penicillin sensitive, in contrast to many isolates causing uncomplicated gonorrhea. We questioned whether any of the known chromosomal mutations to low-level penicillin resistance might adversely affect virulence. The penA2 locus is known to result in low-level resistance to penicillins, whereas mtr-2 results in nonspecific resistance to a variety of antimicrobial agents. We found that the penA2 and mtr-2 mutations each markedly increased sensitivity of strain FA19 to oxygen-independent killing by human polymorphonuclear leukocyte mixed or isolated azurophilic granule extracts. The penA2 and mtr-2 mutations had no effect on sensitivity to serum antibody and complement. Isogenic opaque or transparent variants of several strains of Neisseria gonorrhoeae were equally resistant to human polymorphonuclear leukocyte mixed granule extract bactericidal systems. There were also no differences in susceptibility of piliated type 1 and nonpiliated type 4 variants to human polymorphonuclear leukocyte mixed granule extracts. Since the penA2 and mtr-2 loci are known to increase the degree of cross-linking of cell wall peptidoglycan, the structure of peptidoglycan apparently affects sensitivity to killing by one or more polymorphonuclear leukocyte azurophilic granule extract bactericidal systems. These observations might explain why gonococci with mutations similar to penA2 and mtr-2 are almost never isolated from patients with disseminated gonococcal infection.

Cleavage of membrane bound C3bi, an intermediate of the third component of complement, to C3c and C3d-like fragments by crude leucocyte lysosomal lysates and purified leucocyte elastase

Partial degradation of the biologically-active major fragment of the third complement component (C3b) to C3bi is catalysed by the endopeptidase C3b inactivator (I) and its co-factor, beta 1H globulin (H). Complete degradation to the fragments C3c and C3d requires an additional protease, which can be simulated in vitro by trypsin. This study was designed to identify the in vivo correlate of trypsin. Purified and 125I-labelled C3b bound to sheep erythrocytes was used as substrate. Release of label into the supernate served as an index of proteolysis. The chain structure of the peptides in the supernate or remaining bound to the erythrocytes was assessed by SDS polyacrylamide gel electrophoresis. Significant cleavage of cell-bound C3b was obtained by treatment with I, H and extracts from human peripheral blood leucocyte azurophil granules. Purified elastase also removed label in the presence of I and H. The peptide remaining on the cell had the characteristic 33K molecular weight of C3d. The activity of elastase in cleaving was blocked by alpha-1-anti-trypsin, the chloromethyl ketone, MeO-Suc-Ala-Pro-Val-Ch2Cl and by rabbit antibody to elastase. Thus, elastase purified from azurophil granules of human polymorphonuclear neutrophils (PMN) is a potent catalyst of the cleavage of C3bi to C3c- and C3d-like fragments and may contribute in vivo to the control of complement-mediated inflammation.

Bactericidal activity in fractionated granule contents from human polymorphonuclear leukocytes: studies with leukocytes from normal individuals

Sephadex G-100 chromatographic fractions of granule extracts from normal human polymorphonuclear leukocytes, exhibiting differences from fractions previously obtained from leukemic polymorphonuclear leukocytes, possessed cationic proteins with distinct bactericidal activity against cell wall mutants of Salmonella typhimurium LT2.

Protease inhibitors in inflammatory synovial effusions

Granulocyte lysosomal enzymes can potentially participate in cartilage degradation in inflammatory arthritides. However, we have shown that the quantity of several such enzymes in an inflammatory synovial effusion correlates negatively with the degree of radiographic damage of the joint from which the fluid was sampled. In the current work the quantity of the following 5 protease inhibitors was determined immunochemically in the same fluids: alpha 1 antitrypsin, alpha 1-antichymotrypsin, alpha 2-macroglobulin, inter-alpha-trypsin inhibitor, and Cl esterase inhibitor. These inhibitors are generally covariate and correlate positively with the total protein in the fluid as well as the number of granulocytes and the concentration of granulocyte lysosomal enzymes in the fluid. As did the lysosomal enzymes, the protease inhibitors correlate negatively with radiographic destruction. It is likely that lysosomal enzymes in solution in inflammatory synovial effusions are rendered effete by the presence of protease inhibitors.

Compartmentalization of cyclic AMP during phagocytosis by human neutrophilic granulocytes

Immunocytochemistry shows that early during phagocytosis of zymosan, adenosine 3',5'-monophosphate (cyclic AMP) appears on the cell surface before the phagosome is internalized. The appearance of cyclic AMP on the cell surface is coincident with that of granule products and regulatory subunit of type I cyclic AMP-dependent protein kinase. Guanosine 3',5'-monophosphate is not associated with the initiation site of phagocytosis, but is observed throughout the granular cytoplasmic region. This sharply localized accumulation of cyclic AMP may serve as a signal for the initiation of phagocytosis.