The etiology of community-acquired pneumonia at an urban public hospital: influence of human immunodeficiency virus infection and initial severity of illness

In a prospective study, the etiology of community-acquired pneumonia (CAP) was investigated among consecutive patients admitted to an academic, urban public hospital in Seattle. The study population was uniquely young, was predominantly male, and had high rates of homelessness, cigarette smoking, alcoholism, injection drug use, and human immunodeficiency virus (HIV) infection. Leading causes of CAP among HIV-negative patients were aspiration, followed by Streptococcus pneumoniae, Legionella species, and Mycoplasma pneumoniae. Among HIV-positive patients, Pneumocystis carinii, Mycobacterium tuberculosis, S. pneumoniae, and M. pneumoniae were the most common etiologic agents. Severe CAP was associated with typical bacterial infections and aspiration pneumonia but not Legionella infection among HIV-negative patients and with Pseudomonas aeruginosa infections among HIV-positive patients. These findings emphasize the need to tailor empirical antibiotic therapy according to local patient populations and individual risk factors and highlight the importance of recognizing underlying HIV infection in patients who are hospitalized with CAP.

Modulation of neutrophil-mediated activity against the pseudohyphal form of Candida albicans by granulocyte colony-stimulating factor (G-CSF) administered in vivo

Renewed interest in neutrophil transfusions has emerged with the development and clinical use of granulocyte colony-stimulating factor (G-CSF). G-CSF not only increases neutrophil (polymorphonuclear leukocyte, PMNL) production but also modulates various physiological properties of PMNL. The effects of G-CSF on PMNL-mediated fungicidal activity were evaluated by administration of G-CSF (300 micrograms/day subcutaneously) to 5 healthy volunteers for 6 days. G-CSF significantly enhanced PMNL-mediated damage of Candida albicans pseudohyphae by 33% (P=.007) on day 2 and by 44% (P=.04) on day 6 at a 10:1 effector:target ratio. In contrast, the ability of PMNL to induce damage of hyphae from either Fusarium solani or Aspergillus fumigatus did not significantly change during the study period. These data demonstrate that G-CSF administered in vivo modulates PMNL-mediated fungicidal activity against the pseudohyphal form of C. albicans, thereby suggesting potential utility of G-CSF as a biologic response-modifying therapy in some opportunistic fungal infections.

Comparison of interferon-gamma, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor for priming leukocyte-mediated hyphal damage of opportunistic fungal pathogens

Proinflammatory cytokines have been proposed as adjunctive therapeutic agents to enhance the host immune response during infections caused by opportunistic fungi. The study compared the differential in vitro priming effects of interferon-gamma (IFN-gamma), granulocyte colony-stimulating factor (G-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) on hyphal damage of opportunistic fungi mediated by isolated neutrophils (polymorphonuclear leukocytes, PMNL) and buffy coat cells (polymorphonuclear leukocytes/peripheral blood mononuclear cells, PMNL/PBMC) from healthy donors. IFN-gamma (1000 U/mL) effectively primed both PMNL and PMNL/PBMC for enhanced hyphal damage of Aspergillus fumigatus, Fusarium solani, and Candida albicans. G-CSF (100 ng/mL) increased hyphal damage mediated by both PMNL and PMNL/PBMC against F. solani, and GM-CSF (100 ng/mL) augmented the antifungal activity of PMNL/PBMC against hyphal forms of both F. solani and C. albicans. IFN-gamma may be superior to G-CSF or GM-CSF for enhancing the microbicidal activity of PMNL and PMNL/PBMC against opportunistic fungi.

Granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor: comparisons and potential for use in the treatment of infections in nonneutropenic patients

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) enhance the antimicrobial functions of mature neutrophils. G-CSF differs from GM-CSF in its specificity of action on developing and mature neutrophils, its effects on neutrophil kinetics, and its toxicity profile. The toxicity profile of recombinant (r) GM-CSF is consistent with priming of macrophages for increased formation and release of inflammatory cytokines, whereas rG-CSF induces production of antiinflammatory factors, such as interleukin-1 receptor antagonist and soluble tumor necrosis factor receptors, and is protective against endotoxin- and sepsis-induced organ injury. The low toxicity of rG-CSF, results of animal models of infection, and extensive experience with neutropenic subjects have promoted clinical studies in nonneutropenic subjects, which indicate that rG-CSF may be beneficial as adjunctive therapy for treatment of serious bacterial and opportunistic fungal infections in nonneutropenic patients, including those with alterations in neutrophil function.

Teaching compassion and respect. Attending physicians' responses to problematic behaviors

OBJECTIVE

To describe how and why attending physicians respond to learner behaviors that indicate negative attitudes toward patients.

SETTING

Inpatient general internal medicine service of a university-affiliated public hospital.

PARTICIPANTS

Four ward teams, each including an attending physician, a senior medicine resident, two interns, and up to three medical students.

DESIGN

Teams were studied using participant observation of rounds (160 hours); in-depth semistructured interviews (n = 23); a structured task involving thinking aloud (n = 4, attending physicians); and patient chart review. Codes, themes, and hypotheses were identified from transcripts and field notes, and iteratively tested by blinded within-case and cross-case comparisons.

MAIN RESULTS

Attending physicians identified three categories of potentially problematic behaviors: showing disrespect for patients, cutting corners, and outright hostility or rudeness. Attending physicians were rarely observed to respond to these problematic behaviors. When they did, they favored passive nonverbal gestures such as rigid posture, failing to smile, or remaining silent. Verbal responses included three techniques that avoided blaming learners: humor, referring to learners' self-interest, and medicalizing interpersonal issues. Attending physicians did not explicitly discuss attitudes, refer to moral or professional norms, "lay down the law," or call attention to their modeling, and rarely gave behavior-specific feedback. Reasons for not responding included lack of opportunity to observe interactions, sympathy for learner stress, and the unpleasantness, perceived ineffectiveness, and lack of professional reward for giving negative feedback.

CONCLUSIONS

Because of uncertainty about appropriateness and effectiveness, attending physicians were reluctant to respond to perceived disrespect, uncaring, or hostility toward patients by members of their medical team. They tended to avoid, rationalize, or medicalize these behaviors, and to respond in ways that avoided moral language, did not address underlying attitudes, and left room for face-saving reinterpretations. Although these oblique techniques are sympathetically motivated, learners in stressful clinical environments may misinterpret, undervalue, or entirely fail to notice such subtle feedback.

Bartonella (Rochalimaea) quintana bacteremia in inner-city patients with chronic alcoholism

BACKGROUND

Bartonella (Rochalimaea) quintana is a fastidious gram-negative bacterium known to cause trench fever, cutaneous bacillary angiomatosis, and endocarditis. Between January and June 1993 in Seattle, we isolated B. quintana from 34 blood cultures obtained from 10 patients not known to be infected with the human immunodeficiency virus (HIV).

METHODS

After identifying the isolates as B. quintana by direct immunofluorescence and DNA-hybridization studies, we determined strain hybridization with studies of restriction-fragment-length polymorphisms (RFLPs) of the intergenic spacer (noncoding) region of ribosomal DNA amplified by the polymerase chain reaction (PCR). To characterize the epidemiologic and clinical features of bartonella infections in these patients, we performed a retrospective case-control study using as controls 20 patients with blood cultures obtained at approximately the same time as those obtained from the index patients.

RESULTS

B. quintana isolates from the 10 patients were indistinguishable by PCR-RFLP typing. All 10 patients had chronic alcoholism, and 8 were homeless (P = 0.001 for both comparisons with controls). The six patients who underwent HIV testing were seronegative. At the time of their initial presentation, seven patients had temperatures of at least 38.5 degrees C. Six patients had three or more blood cultures that were positive for B. quintana, and in four of these patients B. quintana was isolated from blood cultures obtained 10 or more days apart. Subacute endocarditis developed in two patients and required surgical removal of the infected aortic valve in one of them. Nine patients recovered; one died of sepsis from Streptococcus pneumoniae infection.

CONCLUSIONS

B. quintana is a cause of fever, bacteremia, and endocarditis in HIV-seronegative, homeless, inner-city patients with chronic alcoholism.

Respiratory syncytial virus infections on an adult medical ward

Eleven cases of respiratory syncytial virus (RSV) infection occurred in acutely ill hospitalized adults over a 7-week period. Nosocomial illness was suspected in two patients. Because RSV can cause serious infections in immunocompromised adults with the potential for nosocomial spread, the following recommendations are indicated: (1) during the winter months, early recognition and diagnosis of RSV infections both in hospital staff and in patients should be encouraged; (2) infected hospital personnel should avoid patient contact when possible; (3) during outbreaks, careful attention must be paid to hand washing and gloving; and (4) a high level of vigilance for RSV infection should be maintained on units with immunocompromised patients. Increased awareness of the potential risks of RSV infection is needed on adult medical units.

Expression of leukocyte adherence-related glycoproteins during differentiation of HL-60 promyelocytic leukemia cells

We used the HL-60 human promyelocytic leukemia cell line to analyze the surface expression of a family of adherence-related leukocyte surface antigens during myeloid differentiation. These antigens are composed of discrete alpha subunits, designated alpha L, alpha M, and alpha X, that are each noncovalently associated with a common beta subunit. Monoclonal antibodies directed against the individual subunits served as markers in both indirect immunofluorescence studies and immunoprecipitations from HL-60 cells differentiated preferentially towards mature granulocytes (DMSO, retinoic acid) or monocyte/macrophages (PMA, vitamin D3). In undifferentiated HL-60 cells, the alpha L and alpha X subunits were constitutively expressed, whereas the alpha M subunit was not. Differentiation of HL-60 cells along the granulocytic pathway with DMSO resulted in a marked increase in alpha M and minimal increases in alpha L and alpha X. The phenotypic expression of these antigens on DMSO-treated HL-60 cells closely resembled that on normal circulating PMN. Differentiation along the monocyte/macrophage pathway when using PMA or vitamin D3 resulted in major increases in alpha L and alpha X expression, as well as alpha M. These changes resulted in a surface phenotype characteristic of that present on human monocyte-derived macrophages. Triggering of undifferentiated HL-60 cells with PMA caused no increase in subunit expression, whereas stimulation of DMSO-differentiated HL-60 cells with PMA produced more than a 1.5-fold enhancement of both the alpha M and alpha X subunits, and stimulation of human PMN with PMA increased the surface expression of alpha M more than fourfold and alpha X subunit twofold. Stimulation with PMA produced no change in expression of the alpha L subunit in any of the three cell populations. These results indicate that the alpha subunits of this glycoprotein family can be selectively regulated during in vitro differentiation of a human promyelocytic leukemia cell line. Second, DMSO-differentiated HL-60 cells and human PMN possessed an intracellular pool of alpha M and alpha X, but not alpha L, that could be translocated to the surface. Thus, despite structural and functional relationships among the alpha subunits in this glycoprotein family, they undergo disparate surface expression and intracellular regulation during differentiation.

Expression of leukocyte adherence-related glycoproteins during differentiation of HL-60 promyelocytic leukemia cells

We used the HL-60 human promyelocytic leukemia cell line to analyze the surface expression of a family of adherence-related leukocyte surface antigens during myeloid differentiation. These antigens are composed of discrete alpha subunits, designated alpha L, alpha M, and alpha X, that are each noncovalently associated with a common beta subunit. Monoclonal antibodies directed against the individual subunits served as markers in both indirect immunofluorescence studies and immunoprecipitations from HL-60 cells differentiated preferentially towards mature granulocytes (DMSO, retinoic acid) or monocyte/macrophages (PMA, vitamin D3). In undifferentiated HL-60 cells, the alpha L and alpha X subunits were constitutively expressed, whereas the alpha M subunit was not. Differentiation of HL-60 cells along the granulocytic pathway with DMSO resulted in a marked increase in alpha M and minimal increases in alpha L and alpha X. The phenotypic expression of these antigens on DMSO-treated HL-60 cells closely resembled that on normal circulating PMN. Differentiation along the monocyte/macrophage pathway when using PMA or vitamin D3 resulted in major increases in alpha L and alpha X expression, as well as alpha M. These changes resulted in a surface phenotype characteristic of that present on human monocyte-derived macrophages. Triggering of undifferentiated HL-60 cells with PMA caused no increase in subunit expression, whereas stimulation of DMSO-differentiated HL-60 cells with PMA produced more than a 1.5-fold enhancement of both the alpha M and alpha X subunits, and stimulation of human PMN with PMA increased the surface expression of alpha M more than fourfold and alpha X subunit twofold. Stimulation with PMA produced no change in expression of the alpha L subunit in any of the three cell populations. These results indicate that the alpha subunits of this glycoprotein family can be selectively regulated during in vitro differentiation of a human promyelocytic leukemia cell line. Second, DMSO-differentiated HL-60 cells and human PMN possessed an intracellular pool of alpha M and alpha X, but not alpha L, that could be translocated to the surface. Thus, despite structural and functional relationships among the alpha subunits in this glycoprotein family, they undergo disparate surface expression and intracellular regulation during differentiation.

Monoclonal antibodies binding to the human neutrophil C3bi receptor have disparate functional effects

Three monoclonal antibodies (MAb)--OKMI, 7C3, and 60.3--immunoprecipitated a common 170-kd neutrophil membrane antigen closely associated with, or identical to, the C3bi receptor (CR3). Despite binding to a common receptor, these antibodies displayed marked differences in their effects on C3bi-mediated neutrophil function as assessed by the binding and ingestion of opsonized zymosan and the subsequent triggering of the respiratory burst. Antibody 7C3 caused a time-dependent, irreversible inhibition of the neutrophil oxidative response to opsonized zymosan that correlated with capping of the bound antibody. In contrast, antibody 60.3 caused an immediate inhibition of the neutrophil oxidative response to opsonized zymosan that required the continuous presence of exogenous antibody to achieve the maximal inhibitory effect. Antibody OKMI demonstrated minimal inhibition of O2- release. Despite their functional differences, binding of either 7C3 or 60.3 led to up-regulation of new antigen, presumably from intracellular sites as previously described using OKMI. Crossed immunoprecipitations of radiolabeled neutrophil lysates indicated that each MAb bound to different antigens near or within the CR3 complex. Thus three MAb binding to the neutrophil CR3 receptor each caused receptor up-regulation but had markedly different functional effects on the cell.

D-Penicillamine: analysis of the mechanism of copper-catalyzed hydrogen peroxide generation

Recent studies have suggested that the inhibition of lymphocyte mitogenesis by D-penicillamine in the presence of copper could be mediated by the formation and action of hydrogen peroxide. To explore this possibility further, we first sought evidence of H2O2 generation by D-penicillamine in a cell-free system by a) measurement of copper-catalyzed D-penicillamine oxidation and the requirement for oxygen in this process; b) direct measurement of H2O2 formation during D-penicillamine oxidation by the peroxidase-mediated oxidation of fluorescent scopoletin; and c) evaluation of the possible synthesis of O2- during D-penicillamine oxidation. The addition of copper to D-penicillamine in physiologic buffer catalyzed D-penicillamine oxidation in a dose-dependent fashion. D-penicillamine oxidation was accompanied by O2 consumption with a molar ratio of approximately 2:1, but did not occur under anaerobic conditions. Furthermore, D-penicillamine oxidation resulted in the formation of amounts of H2O2 stoichiometrically equivalent to oxygen consumption (i.e., 1:1). Copper-catalyzed D-penicillamine oxidation caused reduction of nitroblue tetrazolium in a reaction blocked by superoxide dismutase, suggesting the formation of O2-. Additional studies confirmed that D-penicillamine inhibited PHA-induced mitogenesis of lymphocytes in the presence of copper, and that catalase protected the cells from this action. Furthermore, when polymorphonuclear leukocytes were incubated with D-penicillamine plus copper, hexose monophosphate shunt activity increased up to threefold with abrogation of this stimulation by catalase. None of the effects of D-penicillamine plus copper on cells were diminished by hydroxyl radical scavengers mannitol or benzoate. These results are consistent with oxygen-dependent copper-catalyzed oxidation of D-penicillamine in aqueous solutions leading to the formation of O2- and H2O2. H2O2 produced by this reaction can inhibit lymphocyte mitogenesis and stimulate neutrophil hexose monophosphate shunt activity in vitro and may be relevant to the therapeutic effects of D-penicillamine in vivo.

D-Penicillamine: analysis of the mechanism of copper-catalyzed hydrogen peroxide generation

Recent studies have suggested that the inhibition of lymphocyte mitogenesis by D-penicillamine in the presence of copper could be mediated by the formation and action of hydrogen peroxide. To explore this possibility further, we first sought evidence of H2O2 generation by D-penicillamine in a cell-free system by a) measurement of copper-catalyzed D-penicillamine oxidation and the requirement for oxygen in this process; b) direct measurement of H2O2 formation during D-penicillamine oxidation by the peroxidase-mediated oxidation of fluorescent scopoletin; and c) evaluation of the possible synthesis of O2- during D-penicillamine oxidation. The addition of copper to D-penicillamine in physiologic buffer catalyzed D-penicillamine oxidation in a dose-dependent fashion. D-penicillamine oxidation was accompanied by O2 consumption with a molar ratio of approximately 2:1, but did not occur under anaerobic conditions. Furthermore, D-penicillamine oxidation resulted in the formation of amounts of H2O2 stoichiometrically equivalent to oxygen consumption (i.e., 1:1). Copper-catalyzed D-penicillamine oxidation caused reduction of nitroblue tetrazolium in a reaction blocked by superoxide dismutase, suggesting the formation of O2-. Additional studies confirmed that D-penicillamine inhibited PHA-induced mitogenesis of lymphocytes in the presence of copper, and that catalase protected the cells from this action. Furthermore, when polymorphonuclear leukocytes were incubated with D-penicillamine plus copper, hexose monophosphate shunt activity increased up to threefold with abrogation of this stimulation by catalase. None of the effects of D-penicillamine plus copper on cells were diminished by hydroxyl radical scavengers mannitol or benzoate. These results are consistent with oxygen-dependent copper-catalyzed oxidation of D-penicillamine in aqueous solutions leading to the formation of O2- and H2O2. H2O2 produced by this reaction can inhibit lymphocyte mitogenesis and stimulate neutrophil hexose monophosphate shunt activity in vitro and may be relevant to the therapeutic effects of D-penicillamine in vivo.

Enhanced killing of penicillin-treated gram-positive cocci by human granulocytes: role of bacterial autolysins, catalase, and granulocyte oxidative pathways

Staphylococci pretreated with subminimal inhibitory concentrations (subMIC) of cell-wall active antibiotics exhibit increased susceptibility to killing by human polymorphonuclear leukocytes (PMNs), even when phagosome information is impaired by the mold metabolite, cytochalasin B. To investigate the role of specific bacterial factors in the process, studies were carried out with organisms lacking catalase (streptococci) or cell-wall autolytic enzymes and compared to findings with Staphylococcus aureus 502A. Neutrophil factors were studied using inhibitors, oxygen radical scavengers, myeloperoxidase (MPO)-deficient PMNs, or PMNs from a patient with chronic granulomatous disease (CGD). Documentation of the enhanced susceptibility of the streptococcal strains to killing by PMNs following subMIC penicillin pretreatment required the use of cytochalasin B. Enhancement of killing occurred independent of the presence or absence of bacterial autolysins or catalase. SubMIC penicillin pretreatment of S. pneumoniae R36A specifically promoted the susceptibility of these organisms to killing by myeloperoxidase (MPO)-mediated mechanisms (enhancement lost using MPO-deficient or azide-treated cells). Factors other than MPO or toxic oxygen products generated by the PMN respiratory burst are responsible for enhanced killing of penicillin-pretreated S. aureus 502A (enhancement preserved using MPO-deficient, azide-treated, or chronic granulomatous disease patient cells). These studies define methods to study the interaction of antimicrobial agents and PMNs in the killing of microorganisms. They also demonstrate that penicillin treatment can change the susceptibility of gram-positive cocci to the action of specific PMN microbicidal mechanisms. The mechanism of the enhancement appears to be bacterial strain-dependent and not predictable by bacterial autolysin or catalase activity.

Activation of complement by blood transfusion filters

Fresh blood, stored blood and granulocyte concentrates were passed through 170-micron and microaggregate blood filters to determine the degree of complement activation that occurs during transfusion of citrated blood products. Complement activation was assessed by measurement of C3 conversion using crossed immunoelectrophoresis and by assessment of C5a using a leukocyte aggregation functional assay. Prefiltration, fresh or stored blood products showed 0-1% C3 activation. Postfiltration, the degree of C3 conversion did not change for fresh blood or granulocyte concentrates. For stored whole blood, the degree of C3 conversion increased slightly to 2-3%. Prefiltration results for all samples showed a low level of C5a which did not change after passage through any filter. Serum incubated with filter material at 37 degrees C showed 2-10% C3 conversion. In contrast, results with citrated plasma showed less than 3% conversion of C3. We conclude that although some filter materials may activate complement in serum, filtration of citrated blood products through microaggregate blood filters induces little complement activation.

Inhibition of zymosan activation of human neutrophil oxidative metabolism by a mouse monoclonal antibody

We have studied a neutrophil-specific murine monoclonal antibody, PMN7C3 (IgG3), which specifically alters PMN oxidative metabolism stimulated by serum-opsonized zymosan (STZ) or Candida albicans (STC). Polymorphonuclear cells (PMNs) exposed to PMN7C3 show a significant depression in O2- release (52.8% +/- 2.5% of control), H2O2 release (44.4% +/- 6.0% of control), and O2 consumption (73.9% +/- 2.6% of control) in response to STZ. O2 release in response to phorbol myristate acetate (PMA) was modestly reduced (78.4% +/- 3.7%) by PMN7C3 treatment, but not to the extent seen with STZ or STC. PMN7C3 did not affect O2 release by PMNs stimulated by zymosan opsonized with IgG or by S. aureus, A 23187, or FMLP. PMN7C3 was not cytotoxic, did not trigger oxidative metabolism when used as a stimulus, did not alter STZ-induced degranulation, and did not interfere with binding or uptake of STZ by PMNs. Exposure of PMNs to PMN7C3 decreased PMN rosette formation with erythrocytes coated with C3b (54% of control) or C3bi (63% of control), but had no affect on rosette formation with IgG-coated erythrocytes. PMN7C3 does not bind to monocytes and had no affect on rosette formation by this cell type. Binding of antibody PMN7C3 to the neutrophil surface inhibits the oxidative response to opsonized STZ or STC, possibly in part by altering the function or expression of C3b and C3bi receptors. Monoclonal antibodies such as PMN7C3 provide highly specific probes that may be used to define the molecular features of the stimulus-coupled response of PMN activation.

Biochemical and immunologic analysis of hereditary myeloperoxidase deficiency

Myeloperoxidase (MPO), a heme enzyme present in the azurophilic granules of human polymorphonuclear neutrophils (PMN), is important in the oxygen-dependent microbicidal activity of PMN. MPO deficiency, defined as the lack of PMN peroxidative activity, is a common genetic defect of human PMN. The purpose of our study was to characterize the structural basis for this loss of enzymatic activity, using protein biochemical and immunochemical techniques to examine PMN from three subjects with partial MPO deficiency and from five subjects with complete MPO deficiency.We purified MPO from normal PMN and defined its electrophoretic mobility after two-dimensional electrophoretic separation, using nondenaturing acidic polyacrylamide gel electrophoresis (PAGE) followed by sodium dodecyl sulfate (SDS) denaturation and SDS-PAGE separation of MPO subunit peptides. In agreement with previous studies, we found that normal MPO had subunits of 59,000 and 13,500 mol wt when subjected to SDS-PAGE under reducing conditions. Granule protein extracts of normal PMN, partially MPO-deficient PMN, and completely MPO-deficient PMN were analyzed with two-dimensional PAGE. Partially MPO-deficient PMN granules contained electrophoretically normal MPO in less than normal amounts, whereas completely MPO-deficient PMN granules contain no protein with the electrophoretic mobility of normal MPO. Using rabbit antiserum against purified MPO, we used immunoautoradiographic analysis to examine whole PMN for peptides immunochemically related to MPO. PMN from normal, partially MPO-deficient, and completely MPO-deficient subjects were solubilized in SDS and component peptides separated by SDS-PAGE. The peptides were electroblotted onto nitrocellulose paper that was exposed sequentially to rabbit anti-MPO and (125)I-protein A before autoradiography. Radiolabeled bands were identical when partially purified MPO or normal PMN were compared except that whole PMN contained a small amount of an immunologically cross-reactive membrane associated material of 75,000-90,000 mol wt. Using a modification of this immunoautoradiographic analysis, we quantitated the relative amounts of MPO peptides in PMN. PMN from MPO-deficient subjects contain 41.0-52.3% the amount of MPO peptides present in normal PMN. Similar analysis showed that completely MPO-deficient PMN lacked any peptides corresponding to MPO peptides.We conclude that partial MPO deficiency is characterized by the presence of electrophoretically and immunologically normal MPO in amounts approximately one-half that seen in PMN from normal subjects. Completely MPO-deficient PMN lack any normal MPO peptides. No MPO-deficient subject studied had an immunologically cross-reacting variant of MPO. Since this deficiency is associated with the absence of more than one peptide, it is possible that the underlying genetic defect may involve: (a) failure to synthesize a single precursor peptide; (b) abnormal regulation of the synthesis of two separate peptides; or (c) an aberration in postsynthetic processing or packaging into azurophilic granules.

Enhancement of macrophage Fc-dependent phagocytosis by resident thymocytes: effect of a unique heat-stable lymphokine

Lymphocytes, activated by lectins or specific antigens, have been shown to enhance macrophage phagocytosis through the elaboration of a heat-labile soluble factor(s). Recent evidence from our laboratory revealed that resident (nonactivated) murine thymocytes and splenic lymphocytes increase peritoneal macrophage glucose metabolism through the elaboration of a heat-stable soluble factor(s). Therefore, we investigated the effect of resident lymphocyte subpopulations on macrophage Fc-dependent phagocytosis. Thioglycollate-elicited and resident peritoneal macrophages from BALB/c mice were cultured in serum-free media with syngeneic resident thymocytes or splenic T lymphocytes. Macrophage Fc-dependent phagocytosis was assayed by measuring the ingestion of 51CrSHEA. After 4 days in vitro, resident thymocytes produced a mean 160 (+/- 31) and 136% (+/- 22) increase in Fc-dependent phagocytosis by thioglycollate-elicited (thio-macrophages) and resident peritoneal macrophages, respectively. Splenic T lymphocytes increased thio-macrophage phagocytosis by 112% (+/- 41) under similar conditions. Macrophage Fc-dependent phagocytosis was increased after 24 hr of co-culture by supernatant derived from resident thymocytes and could be further enhanced by supernatant from Con A-activated thymocytes. Supernatant from guinea pig embryo fibroblasts did not increase macrophage phagocytosis. The soluble factor(s) was produced by resident thymocytes after 24 hr of preculture. This factor was active despite heating at 100 degrees C for 30 min whereas the effect of Con A-activated thymocyte supernatant was heat-labile. The stimulatory effect of resident thymocyte supernatant was not observed when the macrophages and supernatant were cultured in 2% FCS. In contrast to the factor(s) produced by resident thymocytes, the factor(s) in FCS that increased phagocytosis was heat-labile. These data suggest thymocytes and splenic T lymphocytes promote macrophage Fc-dependent phagocytosis in the absence of antigenic or lectin stimulation. This previously unrecognized effect of resident thymocytes is due to a unique heat-stable soluble factor(s) that is concealed in the presence of serum.

Enhancement of macrophage Fc-dependent phagocytosis by resident thymocytes: effect of a unique heat-stable lymphokine

Lymphocytes, activated by lectins or specific antigens, have been shown to enhance macrophage phagocytosis through the elaboration of a heat-labile soluble factor(s). Recent evidence from our laboratory revealed that resident (nonactivated) murine thymocytes and splenic lymphocytes increase peritoneal macrophage glucose metabolism through the elaboration of a heat-stable soluble factor(s). Therefore, we investigated the effect of resident lymphocyte subpopulations on macrophage Fc-dependent phagocytosis. Thioglycollate-elicited and resident peritoneal macrophages from BALB/c mice were cultured in serum-free media with syngeneic resident thymocytes or splenic T lymphocytes. Macrophage Fc-dependent phagocytosis was assayed by measuring the ingestion of 51CrSHEA. After 4 days in vitro, resident thymocytes produced a mean 160 (+/- 31) and 136% (+/- 22) increase in Fc-dependent phagocytosis by thioglycollate-elicited (thio-macrophages) and resident peritoneal macrophages, respectively. Splenic T lymphocytes increased thio-macrophage phagocytosis by 112% (+/- 41) under similar conditions. Macrophage Fc-dependent phagocytosis was increased after 24 hr of co-culture by supernatant derived from resident thymocytes and could be further enhanced by supernatant from Con A-activated thymocytes. Supernatant from guinea pig embryo fibroblasts did not increase macrophage phagocytosis. The soluble factor(s) was produced by resident thymocytes after 24 hr of preculture. This factor was active despite heating at 100 degrees C for 30 min whereas the effect of Con A-activated thymocyte supernatant was heat-labile. The stimulatory effect of resident thymocyte supernatant was not observed when the macrophages and supernatant were cultured in 2% FCS. In contrast to the factor(s) produced by resident thymocytes, the factor(s) in FCS that increased phagocytosis was heat-labile. These data suggest thymocytes and splenic T lymphocytes promote macrophage Fc-dependent phagocytosis in the absence of antigenic or lectin stimulation. This previously unrecognized effect of resident thymocytes is due to a unique heat-stable soluble factor(s) that is concealed in the presence of serum.

Role of myeloperoxidase in the respiratory burst of human neutrophils

Myeloperoxidase (MPO), a heme enzyme present in the primary granules of polymorphonuclear leukocytes (PMNs), has been demonstrated to participate in the oxygen-dependent microbicidal activity of these cells. Evidence for the importance of MPO in this role comes in part from studies of normal PMNs treated with the heme enzyme inhibitor, sodium azide. MPO has also been suggested to regulate the respiratory activity of PMNs during phagocytosis. The role of MPO in PMN oxygen metabolism was examined by studying parameters of the respiratory burst of PMNs from a number of unrelated MPO-deficient subjects; in addition, the ability of heme enzyme inhibitors to duplicate the MPO-deficient state was studied by treating normal and MPO-deficient cells with these compounds. MPO-deficient PMNs were found to have a time-dependent hypermetabolic response as assessed by measurement of oxygen consumption, superoxide generation, hydrogen peroxide release, and hexose monophosphate shunt activity. Catabolic pathways for hydrogen peroxide were normal, suggesting the increased recovery of oxygen metabolites reflects increased production rather than decreased catabolism of H2O2. These observations support the concept that MPO may play an important role in terminating the respiratory burst of normal PMNs. The three heme enzyme inhibitors studied--sodium azide, potassium cyanide, and 3-aminotriazole--differed greatly in the degree to which they inhibited various enzymatic systems in the PMN. Nonetheless, as a group, they exerted qualitatively similar effects on oxygen metabolism of normal and of MPO-deficient PMNs. This indicates that many of the mechanisms by which heme enzyme inhibitors influence PMN metabolism are independent of the inhibition of MPO. Conclusions from studies using such treatment of PMNs should be interpreted with caution.

Effect of microaggregate blood filtration on granulocyte concentrates in vitro

To determine the effect of transfusing granulocyte concentrates through microaggregate blood filters, granulocytes prepared with a cell processor were passed through screen and depth microaggregate filters. Pre- and postfiltration evaluations were made of total granulocyte count, levels of muramidase, granulocyte viability, motility, phagocytosis, bactericidal activity, and hydrogen peroxide-forming capacity. Compared to prefiltration levels, a significant (p less than 0.05) decrease in postfiltration granulocyte counts was seen for all the depth filters studied but not for the standard 170 microns (control) or the 40 microns screen filter. For the various tests of granulocyte function evaluated prefiltration, no significant postfiltration differences (p greater than 0.05) were seen for any of the filters studied. Screen microaggregate filters retained only 1 to 3 percent of granulocytes contained in the concentrates, and thus appear satisfactory for use in clinical transfusions. The large percentage of neutrophils retained by the depth filters (20-62%), however, precludes their use for transfusion of granulocyte concentrates.

Genetic disorders of leukocyte function: what they tell us about normal antimicrobial mechanisms of human phagocytic cells

Analysis of three inherited defects of granulocyte function (Chediak-Higashi Syndrome, CHS; Chronic Granulomatous Disease, CGD; Myeloperoxidase Deficiency, MPO) has highlighted critical events for the antimicrobial function of these cells and placed others in perspective. Prompt phagosomal fusion may be more important for digestion of organisms rather than killing as indicated by the mild bactericidal defects in the CHS. The formation of O2- and H2O2 during the phagocytic respiratory burst is central for the broad antimicrobial activity of granulocytes. MPO, on the other hand, while perhaps normally participating in granulocyte antimicrobial action, appears to be essential only for the effective killing of eukaryotic organisms such as certain fungal strains. While the non-oxidative killing mechanism of neutrophils have stimulated much recent interest and were the first to be defined no specific inherited defects have been discovered which are clinically important. Genetic disorders of macrophage effector function remain to be clearly defined as do those of eosinophils. The lessons learned from the study of the granulocyte defects discussed have provided both the technology and approach to the analysis of the antimicrobial and cytocidal mechanisms of these important phagocytic cells.

Neutrophil response and function during acute cytomegalovirus infection in guinea pigs

The mobilization and functional characteristics of polymorphonuclear leukocytes (PMNs) at the site of an inflammatory stimulus were studied during acute cytomegalovirus infection in guinea pigs. Weanling Hartley strain guinea pigs were inoculated subcutaneously with approximately 10(6) 50% tissue culture infective doses of virulent salivary gland-passaged guinea pig cytomegalovirus. The virus was uniformly present in bone marrow, buffy coat, and casein-elicited peritoneal exudate cells 5 to 7 days after the inoculation. The mean numbers of circulating PMNs in the animals were 2,862/microliters in uninfected controls and 880/microliters in infected animals. The total peritoneal PMNs recovered 14 h after casein injection were 491 X 10(6) and 237 X 10(6) in control and infected animals, respectively. The number of 50% tissue culture infective doses of guinea pig cytomegalovirus per 10(6) purified peritoneal PMNs was 10(2.17). Neutrophil O2 consumption was similar in infected and control animals in response to either stimulation by a neutrophil activator, phorbol myristate acetate, or phagocytosis of Staphylococcus aureus. However, the maximal rate of H2O2 release and the percent killing of S. aureus by peritoneal exudate cells from infected animals were significantly reduced compared with uninfected controls during acute infection. Granulocytopenia, a decreased mobilization of PMNs to the site of the inflammatory stimulus, a diminished cellular release of H2O2 in response to a bacterial stimulus, and a modest reduction in bacterial killing were demonstrated during experimental acute cytomegalovirus infection. Such reductions in granulocyte number and function at inflammatory sites during this type of infection could alter antimicrobial defenses.

Myeloperoxidase deficiency: prevalence and clinical significance

Leukocyte differential counting by flow cytochemistry has shown 28 subjects with partial or complete neutrophil myeloperoxidase (MPO) deficiency in a population of about 60 000 patients screened at a general hospital. Partial (13 patients) or complete (13 patients) MPO deficiency was confirmed by examination of cytochemical stains in 26, biochemical measurement of total enzymatic activity in eight, and flow cytometry in six patients. None had apparent hematologic disorders. Only four patients had infections; of these, two had major systemic infections (one, candidiasis; one, bacteremia). In assays of leukocyte function only minor defects in killing of Staphylococcus aureus by MPO-deficient cells were noted whereas killing of Candida albicans was much more impaired. Family studies in eight patients have shown various degrees of partial or complete MPO deficiency in first-degree relatives of six. The findings indicate that the incidence of MPO deficiency is much higher than previously suspected. Although MPO appears to be necessary for killing of Candida species by neutrophils, the importance of its role in normal antibacterial defense must be re-evaluated.

The oxidative metabolism of thioglycollate-elicited mouse peritoneal macrophages: the relationship between oxygen, superoxide and hydrogen peroxide and the effect of monolayer formation

The oxygen and glucose metabolism of peritoneal macrophages harvested from untreated mice (resident cells) and mice given an i.p. injection of thioglycollate broth (thioglycollate cells) were examined. Thioglycollate cells consumed approximately 3 times as much O2 at rest and during phagocytosis as resident cells, but oxygen reduction products (superoxide and hydrogen peroxide) could be recovered in only minimal amounts despite triggering by phagocytosis or exposure to PMA. Indirect evidence for the formation of oxygen reduction products such as O2- by thioglycollate cells was obtained by observation of the major pathways for glucose oxidation and NBT dye reduction. When thioglycollate cells were allowed to adhere to a glass surface O2- and H2O2 were easily recovered in the extracellular medium with a 20-fold increase above cells in suspension exposed to PMA. This study suggests that thioglycollate-elicited macrophages have a vigorous oxidative metabolism but that recovery, and perhaps utilization, of O2 reduction products formed will depend on the conditions of incubation. These events may be significant both for the study of parameters of macrophage "activation" in vitro as well as the function of these cells in vivo.

The oxidative metabolism of thioglycollate-elicited mouse peritoneal macrophages: the relationship between oxygen, superoxide and hydrogen peroxide and the effect of monolayer formation

The oxygen and glucose metabolism of peritoneal macrophages harvested from untreated mice (resident cells) and mice given an i.p. injection of thioglycollate broth (thioglycollate cells) were examined. Thioglycollate cells consumed approximately 3 times as much O2 at rest and during phagocytosis as resident cells, but oxygen reduction products (superoxide and hydrogen peroxide) could be recovered in only minimal amounts despite triggering by phagocytosis or exposure to PMA. Indirect evidence for the formation of oxygen reduction products such as O2- by thioglycollate cells was obtained by observation of the major pathways for glucose oxidation and NBT dye reduction. When thioglycollate cells were allowed to adhere to a glass surface O2- and H2O2 were easily recovered in the extracellular medium with a 20-fold increase above cells in suspension exposed to PMA. This study suggests that thioglycollate-elicited macrophages have a vigorous oxidative metabolism but that recovery, and perhaps utilization, of O2 reduction products formed will depend on the conditions of incubation. These events may be significant both for the study of parameters of macrophage "activation" in vitro as well as the function of these cells in vivo.

Fungal infection in chronic granulomatous disease. The importance of the phagocyte in defense against fungi

Among 245 cases of chronic granulomatous disease which were evaluated, fungal infection occurred in 20.4 percent. Fungi encountered include Aspergillus, Torulopsis and Candida. In 18 percent of the patients with fungal infection, the disease was limited to soft tissue or bone; all did well. Most of the patients had fungal pneumonia and/or widely disseminated disease; diagnosis was usually confirmed by open lung biopsy. Patients with pneumonia or disseminated disease who received no therapy succumbed to infection, whereas more than half the patients who received antifungal therapy were cured. Modalities of treatment included antifungal chemotherapy, surgical removal of infected tissue and granulocyte transfusion. Although several patients showed dramatic improvement during granulocyte transfusions given in combination with antifungal chemotherapy, the improvement achieved was not statistically significant when compared with that achieved with chemotherapy alone. These results emphasized the importance of phagocytic cells in defense against fungi and the need for further evaluation of granulocyte transfusion therapy in compromised hosts in whom fungal infections develop.

Interactions between antibiotics and human neutrophils in the killing of staphylococci

Normal and antibiotic-pretreated staphylococci were incubated with human neutrophils to determine the interactions between cells and antimicrobials in the killing of the organisms. Staphylococcus aureus 502A pretreated during log-phase growth with subinhibitory ((1/4) minimum inhibiting concentration) (MIC) concentrations of penicillin G were more susceptible to killing by normal neutrophils than untreated bacteria (intracellular survival 0.17+/-0.04 vs. 1.5+/-0.38%, mean+/-SEM, respectively, at 35 min in 14 experiments; P < 0.01 by t test). Furthermore, this enhanced susceptibility to killing was observed even when phagosome formation was inhibited by cytochalasin B (65.6+/-4.6% pencillintreated vs. 30.5+/-4.5% untreated killed at 30 min in 14 experiments, P < 0.001). Pretreatment of S. aureus with vancomycin similarly enhanced susceptibility to killing by cytochalasin B-treated polymorphonuclear leukocytes (PMN), whereas pretreatment with gentamicin did not. The enchancement of killing by pretreatment with cell wall-active antibiotics was present in a dose-response fashion to 1/16th the MIC. It required specific antimicrobial activity; i.e., penicillin activity was inhibited by penicillinase or by incubation with bacteria at 4 degrees C. It also required active cellular metabolism and intact neutrophils. For antibiotic-pretreated bacteria to be killed by normal and cytochalasin B-treated cells, phagocytosis or binding to the cells was essential via a serum opsonindependent mechanism. In experiments with the cytochalasin B-treated cells, all bound penicillin-treated bacteria were killed vs. only a fraction (70%) of the bound untreated bacteria. Penicillin in 10 times the MIC had no direct effects on PMN phagocytic, metabolic, or microbicidal functions against a nonsusceptible organism, Candida albicans. The results indicate a cooperative effect between cell wall-active antibiotics at low concentrations and human PMN in the killing of staphylococci. The model establishes conditions for the study of the mechanisms involved in the cooperation of these bactericidal systems.

Enterococcal meningitis: combined vancomycin and rifampin therapy

Intrathecal vancomycin and oral rifampin have been used together to successfully treat a patient with enterococcal meningitis who was allergic to penicillin and who had failed a course of treatment with chloramphenicol. This therapy was tolerated very well and represents an alternate mode of therapy which should be considered in penicillin allergic patients with enterococcal meningitis.

The role of antibody and complement in phagocytosis by rabbit alveolar macrophages

The relative importance of antibody and complement in the phagocytosis of Staphylococcus aureus and Pseudomonas aeruginosa, two common bacterial pathogens, by alveolar macrophages from rabbits was studied. Normal rabbit serum was a satisfactory opsonin for the phagocytosis of S. aureus but not for P. aeruginosa. Normal rabbit serum opsonized S. aureus by both the classic and the alternative complement pathways; loss of both pathways destroyed opsonic activity. The presence of complement was not required for maximal phagocytosis when 10% staphylococcal immune serum was used. However, an intact alternative complement pathway enhanced phagocytosis when the concentration of staphlyococcal immune serum was lowered to 0.3%. Similarly, 10% pseudomonas immune serum opsonized P. aeruginosa without complement. When the concentration of pseudomonas immune serum was lowered to 1%, either the classic or the alternative complement pathway could significantly enhance phagocytosis of P. aeruginosa. Similar results were obtained with alveolar macrophages activated with bacille Calmette-Guérin. These studies demonstrate the importance of complement in enhancing phagocytosis by alveolar macrophages of bacterial pathogens when antibody concentration is the limiting factor.

Possible nosocomial transmission of group Y Neisseria meningitidis among oncology patients

Within 4 days, two oncology patients in the Clinical Research Unit had bacteremia causes by group Y Neisseria meningitidis. Three additional patients, identified by prevalence survey, were found to have nasopharyngeal colonization with that serogroup, compared with only one employee (not associated with patients) and no family contacts. Infected and colonized (case) patients were located in the same or adjacent rooms but did not have close contact. A comparison of host and risk factors showed no significant differences between case patients and the other (control) patients located in the same rooms. In retrospect, the index patient, who had marked sputum production but was not isolated, had unrecognized meningococcal pneumonia and probably was the hospital source of a heavy, airborne dispersal of organisms to other patients. Respiratory isolation is warranted for patients with suspected N. meningitidis infection.

Indium-111-labeled human polymorphonuclear leukocytes: viability, random migration, chemotaxis, bacterial capacity, and ultrastructure

Human polymorphonuclear leukocytes (PMNs) were labeled with indium-111 oxine in ethanol, and the effects of the labeling procedure, radioactivity, and concentrations of oxine and ethanol on PMN function and structure were studied in vitro. The standard labeling procedure did not alter the viability, random migration, chemotaxis, bactericidal capacity, or the ultrastructure of PMNs. Exposure to higher doses of radioactivity, or to higher concentrations of ethanol, had no appreciable effects on random migration and chemotaxis of PMNs. A dose-dependent reduction in their random migration and chemotaxis was observed when higher concentrations of oxine were used. These results indicate that In-111-labeled PMNs are structurally intact and have normal in vitro locomotion and bactericidal activity. Indium-111-labeled PMNs should be suitable for studying the kinetics and distribution of these cells in health and disease.

Granulocyte function during lithium therapy

Random migration, chemotaxis, phagocytosis, and bactericidal ability of neutrophils from 5 patients receiving lithium carbonate were compared with those of neutrophils from healthy donors. These cells functioned normally in all respects. Neither sera from patients receiving lithium carbonate nor the addition of lithium chloride to control cells in vitro significantly altered their functional capacity. These findings suggest that neutrophil function in patients receiving lithium therapy is preserved, and they support the potential utility of this drug as a leukopoietic agent in neutropenic states.

Neutrophil function and host resistance

The part played by the phagocytic cells against invading pathogens has been known since the work of Metchnikoff nearly a century ago. This review deals primarily with the role of the neutrophilic polymorphonuclear leukocyte in host defense against microbial infections. The overall function of these cells in protection from infection is dependent on a number of steps. First, an adequate number of functionally mature neutrophils have to be produced and released into the circulation by the bone marrow. Cells must circulate normally and be capable of adhering to capillary and venule walls overlying inflammatory sites. The next step involves the exit of phagocytes from the blood stream through the capillary wall and emigration into the tissues to establish contact with the invading pathogens. This process is accomplished by the locomotive characteristics of these cells and chemotaxis. Most organisms must then be phagocytized to be killed. Two discrete phases are involved in phagocytosis; the "recognition" and attachment phase followed by the ingestion phase. After phagocytosis a series of coordinated morphologic and biochemical events are set into motion which leads to eventual death and lysis of the ingested microbes. A variety of antimicrobial mechanisms are involved in this final step and indicate that these cells have an appreciable reserve capacity if one mechanism is impaired. Recent evidence which clarifies mechanisms involved in all these stages is discussed.

Glucose-6-phosphate dehydrogenase deficiency and infection: a study of hospitalized patients in Iran

The Mediterranean variant of glucose-6-phosphate dehydrogenase (G6PD) is functionally deficient and found in a variety of cell types of affected individuals, including both erythocytes and neutrophils. To determine if the presence of this sex-linked gene is associated to any degree with the occurrence of severe bacterial infection, a study of hospitalized male patients in Iran was undertaken. As determined by erythrocyte assay, allele prevalence in male patients with infection was 22% vs. 12% in a patient group matched for the absence of other risk factors for infection and 6% in a second group who had additional risk factors for infection. When the control and patient groups were considered together the difference between the frequency of G6PD deficiency (10.2%) was significantly different from that found in the infected patients (p less than .05). Furthermore, the mean age of infected patients with G6PD deficiency was significantly less than that of infected patients without G6PD deficiency or non-infected control groups. These data suggest that host defenses may be altered in G6PD deficiency so that bacterial infections are more severe. Alternatively, G6PD deficiency and infection might represent concomittant risk factors which lead to hospitalization during bacterial infection. Potential mechanisms by which host defenses might be altered in G6PD deficiency are discussed.