RESUMEN

Twenty cases of vertebral osteomyelitis from three community hospitals were reviewed. Routine spine radiographs were frequently normal in the setting of active vertebral osteomyelitis. Computed tomographic scanning of the spine frequently detected changes in the vertebral end plates that were diagnostic of vertebral osteomyelitis at a time when routine spine radiographs were unrevealing.

Asunto(s)

RESUMEN

An experimental model of pneumococcal bacteremia in guinea pigs has been developed. By use of this model, complement has been shown to play a critical role in clearance of Streptococcus pneumoniae from the bloodstream and in survival of guinea pigs after iv challenge with type 7 S. pneumoniae. In nonimmune animals, complement activation occurs primarily via the alternative pathway. However, anticapsular antibodies increase the rate of clearance of pneumococci primarily via activation of the classical complement pathway. Detailed studies of the reticuloendothelial localization of cleared radiolabeled pneumococci showed that clearance took place primarily in liver and spleen and that anticapsular antibody increased hepatic and decreased splenic sequestration. This effect could be blocked by depleting complement with cobra venom factor. Comparison of nonimmune animals injected with unencapsulated pneumococci or encapsulated types 7 or 12 pneumococci showed that the virulence of these organisms for guinea pigs correlated with the extent of splenic sequestration. Sensitization of encapsulated pneumococci with anticapsular antibodies led to an antibody dose-dependent increase in the rate of bloodstream clearance. Sensitization of encapsulated pneumococci with anticell wall antibodies had no effect on clearance rates despite the ability of these antibodies to bind to the bacteria and to activate and fix complement to the organisms. In vitro studies showed that C3b deposited by these opsonically ineffective antibodies interacted poorly with C3b receptors. Electron microscopic studies showed that C3b deposited by anticapsular antibodies bound to the pneumococcal capsule while C3b deposited by anti-cell wall antibodies did not. Thus, the localization of C3b deposition on the pneumococcus markedly affects its opsonic potential.

Asunto(s)

RESUMEN

To determine the effect of complement on the normal antibody response to T cell-dependent antigens, we immunized normal and C4 deficient guinea-pigs with bacteriophage phi X 174. Following primary immunization with a standard dose (2 X 10(9) PFU/Kg) given intravenously. C4 deficient guinea-pigs produced less antibody than normal guinea-pigs and were unable to maintain measurable antibody levels. Following secondary immunization, antigen clearance of C4 deficient guinea-pigs was delayed and the subsequent antibody response was identical to their primary response without amplification or isotype switch. Increased antigen dose and administration of antigen in adjuvants into footpads improved the responses but did not make them normal. The primary and secondary responses became essentially normal, however, when small amounts of normal guinea-pig serum were given to the deficient animals at the time of the primary (but not the secondary) immunization. We postulate that the contribution of complement to the mature humoral immune response is related to activation of C3. Our data show that antigen initiates a primary immune response. The resultant antigen-antibody complexes interact with complement and are then non-specifically trapped by C3 receptors on dendritic cells, B cells and macrophages. Thus, antigen is selectively accumulated within the lymphoid organs and in turn 'captures' antigen specific B cells by interaction of the trapped antigen with antigen specific sIg. The approximation of specific lymphoid cells, macrophages and antigen permits generation of specific memory cells and ensures prompt, mature antibody response on subsequent antigen exposure.

Asunto(s)

RESUMEN

Complement and the spleen interact in host defense against the encapsulated Pneumococcus, responsible for most OPSI. Splenectomized patients lack splenic phagocytes specialized to clear bacteria coated with only small amounts of IgG from the bloodstream, and they are unable to mount a sufficient antibody response for liver macrophages to overcome the defect.

Asunto(s)

Asunto(s)

RESUMEN

Employing an in vitro bactericidal assay using C4-deficient guinea pig serum (C4D-GPS), we evaluated the ability of the alternative pathway to kill a number of strains of encapsulated and unencapsulated Haemophilus influenzae (HI). Complement activation occurred, but no bactericidal activity was observed against any of the tested HI in nonimmune C4D-GPS without detectable antibody to HI-type b (HIb) capsular polysaccharide (HIb-ps). In the presence of high-titered human anti- (type b) IgG, C4D-GPS killed the encapsulated strains. Restoration of classical pathway activity by the addition of purified C4 to C4D-GPS, which contained antibody to somatic antigens, resulted in killing of some strains of both encapsulated and unencapsulated HI. In nonimmune C4D-GPS the alternative pathway is activated but does not mediate bactericidal activity. The addition of specific high-titered anticapsular IgG results in killing of encapsulated HI by the alternative pathway in guinea pig serum.

Asunto(s)

RESUMEN

We have developed a quantitative assay for cell surface C3bi using 125I-labeled conglutinin. Conglutinin was purified to homogeneity from bovine serum and radiolabeled with 125I Bolton Hunter reagent. Conditions of time, temperature, ionic strength, and cell concentration that optimized the binding of conglutinin to erythrocytes bearing C3bi were then determined. The interaction between conglutinin and C3bi under these conditions was highly specific, since EAC4b3b, EAC4b3d, EAC4b3b-beta IH, and EAC4b treated with serum did not bind radioconglutinin significance better with EA or EAC4b. Using this assay, was examined the kinetics of inactivation of both human and guinea pig C3b bound to erythrocytes and showed that, for both, maximum conglutinin binding occurred after EAC4b3b had been incubated with a source of beta 1H and C3INA for 10 to 20 min at 37 degrees C.l We showed a linear relationship between the number of molecules of C3bi per erythrocyte and the amount of conglutinin bound for both guinea pig and human C3bi. The affinity of conglutinin for cell-bound C3bi was shown to be independent of C3bi density on the erythrocyte surface, and the Kd for conglutinin binding to erythrocytes bearing human C3bi was determined to be 1.3 X 10(-8) M. The number of conglutinin binding sites per erythrocyte as calculated from Scatchard plots was equal to the number of C3bi molecules on the cell surface as determined by direct assay using 125I-labeled C3. Moreover, for both human and guinea pig C3bi, the plot of log (cell surface C3bi) vs log (conglutinin bound) had a slope of 1. These findings imply that a single molecule of C3bi is capable of binding a molecule of conglutinin under the conditions of our assay.

Asunto(s)

RESUMEN

The mechanism of protection of type-specific antipneumococcal antibody and complement in bacteremia was investigated with purified rabbit antibody and a guinea pig model of pneumococcal bacteremia. IgG and IgM were isolated from the sera of rabbits immunized with type 7 pneumococci (Pn), and their binding to Pn was quantitated. The number of antibody-binding sites on the pnuemococcal capsule was also determined. Pn were incubated with various amounts of the immunoglobulin preparations before intravenous injection into nonimmune guinea pigs. Whereas 120 molecules of IgM per Pn were sufficient to enhance bloodstream clearance of Pn, 1,400 molecules of IgG per bacterium were required to produce this effect. As the amount of either IgG or IgM added to the Pn was increased, the rate of bloodstream clearance accelerated. In striking contrast, greater than 1,000 molecules of IgM had no effect on the rate of clearance in C4-deficient guinea pigs, which cannot activate complement via the classic pathway. Similarly, 5,000 molecules of IgG had only minimal effect in C4-deficient guinea pigs, and 24,000 molecules of IgG had no effect in guinea pigs depleted of complement by cobra venom factor. Thus, the in vivo opsonic effects of both IgG and IgM anticapsular antibody are mediated via their ability to activate complement. IgG anti-pneumococcal cell wall antibody, raised by intravenous injection of rabbits with unencapsulated Pn, had no effect on the rate of bloodstream clearance of Pn or on the polymorphonuclear leukocyte killing of type 7 Pn in an in vitro bacterial assay. Because the opsonic effects of anticapsular antibody required complement activation, the ability of anticell wall IgG to activate complement was compared with the two classes of anticapsular antibody. As judged by depletion of C3 and C4 from guinea pig serum, as well as by the fixation of radiolabeled C3 to Pn, IgM anticapsular antibody was the best complement activator. However, anticell wall IgG was somewhat more active than anticapsular IgG in each of these tests of complement activation and fixation. When equivalent amounts of C3 were fixed to Pn by each of the three antibodies, Pn sensitized with IgG and IgM anticapsular antibodies caused immune adherence, whereas Pn sensitized with anticell wall IgG did not. This may explain the failure of anticell wall antibody of mediate complement-dependent phagocytosis of Pn in vivo or in vitro. Although anticell wall IgG is capable of activating complement and fixing C3 to Pn, it is not opsonic; the most likely reason is that the nonopsonic antibody mediates C3 deposition in sites on the Pn that cannot interact efficiently with phagocytic cell C3 receptors.

Asunto(s)

Asunto(s)

RESUMEN

Pneumococci activate the alternative complement (C) pathway in the absence of demonstrable antibody in normal guinea pig serum. They also activate the classical C pathway in the presence of type-specific antibody and perhaps through other mechanisms as well. A quantitative examination was undertaken of the roles of these 2 pathways of C activation in the splanchnic sequestration of 125I-labeled pneumococci, using a-guinea pig model of pneumococcal bacteremia. Normal unimmunized guinea pigs (NIH-GP) localized more than 3 times as many pneumococci to the liver as the spleen during a period when exponential bloodstream clearance was occurring. C4-deficient guinea pigs (C4D-GP) and cobra venom factor-treated guinea pigs (CVF-GP) showed progressively fewer pneumococci cleared by the liver with concomitant increases in the extent of splenic uptake, demonstrating the important role of C in the clearance of bacteria in the unimmunized animal. Immunization of guinea pigs brought about an increase in pneumococcal sequestration by the liver in NIH and C4D-GP but did not affect the localization pattern of CVF-GP. A comparison of reticuloendothelial system (RES) localization patterns with the rate of removal of bacteria from the bloodstream showed a highly significant correlation between increases in splenic sequestration and persistence of bacteremia. Thus, opsonization by C is an important determinant of the RES clearance of pneumococci. Unlike RBC clearance, where C plus IgM leads to hepatic localization, and C plus IgG tends to produce splenic localization, C in the presence or absence of type-specific antibody tends to cause hepatic localization of pneumococci. When C-mediated opsonic activity is less than optimal, the slower clearance of bacteremia that results is accompanied by an increased dependence on splenic sequestration of pneumococci.

Asunto(s)

RESUMEN

Immune response to polyvalent pneumococcal vaccine was measured in normal volunteers and splenectomised patients, by means of a newly developed enzyme-linked immunosorbent assay for pneumococcal antibodies. IgG and IgM responses to eight of the nine polysaccharides tested were markedly impaired in splenectomised patients. The response of splenectomised patients was less than that of the controls in terms of absolute titre of antibody achieved, relative rise in titre (fold increase of post-immunisation titre over pre-immunisation titre), and rate of rise.

Asunto(s)

RESUMEN

The importance of the spleen in host defense against pneumococcal bacteremia has been suggested by a number of experimental models as well as the occurrence of the syndrome of overwhelming pneumococcal sepsis in asplenic individuals. We studied the mechanism of splenic protection against pneumococcal bacteremia using a guinea pig model. Rates of removal of pneumococci from the blood stream in normal and splenectomized guinea pigs were compared with the extent of hepatic and splenic sequestration of radiolabeled organisms for three different types of pneumococci. A relationship was found between the virulence of a pneumococcus for normal guinea pigs, the extent to which it is cleared by the spleen, and the magnitude of the defect in blood stream sterilization induced by splenectomy. The spleen plays an increasingly important role in the clearance of progressively more virulent organisms, for which hepatic clearance cannot compensate. Thus, the division between hepatic and splenic clearance of bacteremia is a key determinant of the outcome of experimental pneumococcal infection.

Asunto(s)

RESUMEN

A particularly virulent form of bacterial endocarditis due to Streptococcus viridans is described in selected patients. The diagnosis of purulent pericarditis and myocardial abscess is delineated. In addition, emphasis is placed on early surgical intervention in the appropriate management of these potentially lethal complications.

Asunto(s)

RESUMEN

We investigated the opsonic requirements for intravascular clearance of pneumococci in guinea pigs and of sensitized erythrocytes in human beings after splenectomy. The impaired clearance of injected pneumococci in splenectomized guinea pigs was corrected by immunization. This improvement in clearance was due to increased hepatic sequestration of organisms. There was a significant delay in antibody-mediated clearance of autologous erythrocytes sensitized with IgG (P < 0.001), although the rate of complement-mediated clearance in splenectomized patients was normal. A fourfold increase in sensitizing antibody resulted in a significant improvement in clearance that was due to increased hepatic sequestration (P < 0.005). One patient who had an intact spleen and who had previously received Thorotrast (thorium oxide) had impaired antibody-mediated clearance despite increased sensitization. These observations suggest that, after splenectomy the remaining macrophages of the reticuloendothelial system require increased amounts of antibody to mediate efficient intravascular clearance of opsonized particles.

Asunto(s)

RESUMEN

Using a guinea pig model fo bacteremia due to Streptococcus pneumoniae serotype 7, opsonization by the classical and alternative pathways of complement activation was studied in immune and nonimmune animals. Depletion of the alternative complement pathway and complement components C3-C9 resulted in a significant, lethal defect of intravascular clearance in both normal and immune animals. Preopsonization corrected the initial clearance defect in complement-depleted animals. Maximal rates of clearance of bacteremia occurred in immune, normal animals, Immune, C4-deficient animals had clearance curves similar to normal, nonimmune animals. Thus, optimal clearance of pneumococcal bacteremia requires an intact alternative an classical pathway of complement activation. In the nonimmune animal, the alternative pathway provides the primary host defense against infection, whereas after immunization, optimal clearance of bacteremia requires an intact classical pathway of complement activation. However, immunization does not alter the lethal clearance defect in complement-depleted animals.

Asunto(s)

RESUMEN

We treated 69 patients who had hereditary angioedema with danazol to alleviate attacks of mucocutaneous angioedema involving the skin, oropharynx, and gastrointestinal tract, and we documented the continued efficacy of danazol for long-term treatment (1 to 6 years) of hereditary angioedema. Significant dose-related, adverse reactions occurred, including weight gain, myalgias, headaches, microscopic hematuria, abnormal liver function tests, anxiety, altered libido, alopecia, dizziness, and nausea. Alterations in menstrual function were consistently observed. About 10% of patients noted masculinizing side effects, such as acne, hirsutism, and voice deepening. We recommend downward titration of danazol dosage to achieve control of attacks and minimize adverse reactions. Periodic monitoring of patients on long-term danazol therapy is essential to avoid undesirable toxicity.

Asunto(s)

Asunto(s)

RESUMEN

Danazol is an effective agent for the prophylaxis of the recurrent attacks of mucocutaneous and visceral swelling which occur in patients with hereditary angioedema (HAE). Danazol apparently increases the synthesis of the inhibitor of the first component of complement which is partially deficient in these heterozygous individuals. The efficacy of danazol in this condition appears to be limited only by the occurrence of adverse effects.

Asunto(s)

RESUMEN

Although considerable progress has been made during the past two decades in the use of androgens to prevent attacks of hereditary angioedema, replacement of the deficient C1-inhibitor protein would provide a useful menas of treatment once an attack has begun. We studied the clinical use of C1 inhibitor that was partly purified on a large scale from pooled plasma. The in vivo efficacy and safety of this protein concentrate were evaluated during 11 intravenous infusions in eight patients with hereditary angioedema. Three patients received the C1-inhibitor preparation during an asymptomatic period. Increases in serum C4 activity provided evidence of the biologic activity of the infused inhibitor. Intravenous administration of the concentrate during acute abdominal or laryngeal attacks of hereditary angioedema in five patients resulted in abatement of symptoms in addition to increased serum C4 activity. No untoward effects of the intravenous administration of the C1 inhibitor were observed in these eight patients. Thus, this C1-inhibitor preparation seems to offer the potential for safe, effective replacement therapy and may provide a means of controlling an attack of hereditary angioedema that is in progress.

Asunto(s)

RESUMEN

Hereditary angioedema (HAE), an auto-somal dominant disorder characterized by attacks of episodic edema is associated with decreased functional levels of the C1 esterase inhibitor. Approximately 85% of patients have lowered antigen levels of a normal inhibitor protein. 15% of patients have normal or elevated antigenic levels of functionless protein. We have examined the response to danazol therapy of patients with the variant HAE phenotypes possessing the abnormal protein in an effort to determine if these patients possess a normal structural C1 inhibitor allele. Four patients with a variant HAE phenotype were treated successfully with danazol. In two patients, distinguished by the presence of a functionless, albumin-bound, C1 inhibitor (phenotype 2), phenotypic analysis of the danazol response by bidirectional immunoelectrophoresis revealed the appearance of the normal C1 inhibitor gene product during danazol therapy. This relatively cathodal C1 inhibitor peak appears in conjunction with the development of nearly normal functional activity. All of the functional C1 inhibitory activity which appeared in the phenotype 2 treatment serum was associated with the electrophoretically normal inhibitor. This normal protein could be separated from the functionless inhibitor protein by immunoadsorption and molecular sieve chromatography. Danazol therapy of the two patients with an electrophoretically normal, functionless C1 inhibitor (phenotype 3) also resulted in a clinical remission associated with development of a significant increment in functional serum C1 inhibitory activity and C1 inhibitor protein. These findings demonstrate that these two HAE phenotypic variants are heterozygous for the normal serum C1 inhibitor, a finding which was not apparent before phenotypic analysis of this serum during danazol therapy. These data provide strong evidence for a basic similarity between the common form of HAE and its phenotypic variants. They also suggest that a structural gene lesion may result in the abnormalities of serum C1 inhibitor function and disease expression in all three of these HAE phenotypes.

Asunto(s)