The Role of Properdin in Killing of Non-Pathogenic Leptospira biflexa.

Properdin (P) is a positive regulatory protein that stabilizes the C3 convertase and C5 convertase of the complement alternative pathway (AP). Several studies have suggested that properdin can bind directly to the surface of certain pathogens regardless of the presence of C3bBb. Saprophytic Leptospira are susceptible to complement-mediated killing, but the interaction of properdin with Leptospira spp. has not been evaluated so far. In this work, we demonstrate that properdin present in normal human serum, purified properdin, as well as properdin oligomers P2, P3, and P4, interact with Leptospira. Properdin can bind directly to the bacterial surface even in the absence of C3b. In line with our previous findings, AP activation was shown to be important for killing non-pathogenic L. biflexa, and properdin plays a key role in this process since this microorganism survives in P-depleted human serum and the addition of purified properdin to P-depleted human serum decreases the number of viable leptospires. A panel of pathogenic L.interrogans recombinant proteins was used to identify putative properdin targets. Lsa30, an outer membrane protein from L. interrogans, binds to unfractionated properdin and to a lesser extent to P2-P4 properdin oligomers. In conclusion, properdin plays an important role in limiting bacterial proliferation of non-pathogenic Leptospira species. Once bound to the leptospiral surface, this positive complement regulatory protein of the AP contributes to the formation of the C3 convertase on the leptospire surface even in the absence of prior addition of C3b.

Complement profile in neonates of different gestational ages.

Blood levels of regulators of the complement system in preterm babies were reported in few studies only. The aim of this study was to set up a complement profile in premature and term babies focusing on the development of blood levels of MBL, key regulatory proteins and on classical pathway activity, which may allow an estimation of potential susceptibility to infection. Complement activity (CH50), levels of mannan-binding lectin (MBL), complement regulators (factors H and I, C1 inhibitor, properdin) and C3a as marker of complement activation were assessed in three groups of healthy newborns: (1) prematures (≤34 weeks); (2) late prematures (>34-<37 weeks) and (3) term neonates (≥37 weeks). CH50 increased with gestational age with lower titres in cord blood than in day 5 post-delivery venous blood. MBL concentrations were not significantly different among groups. Quantitative and functional C1 inhibitor were below adult normal range in prematures <34 weeks and lower in cord blood as compared to day 5. Factor I, factor H and properdin remained below adult values in all groups. Low C3a levels excluded that low complement titres were due to activation-induced consumption. These results demonstrate the relative immaturity of the complement system and its regulation, especially in premature infants.

Ontogeny of complement regulatory proteins - concentrations of factor h, factor I, c4b-binding protein, properdin and vitronectin in healthy children of different ages and in adults.

Previous studies of human in vivo complement protein levels have only compared data for neonates with that from adult sera. Here, we establish the normal concentration ranges of the following complement regulatory proteins in healthy Brazilian children of different age groups (neonates: 1 month-1 year, 1-6 years and 6-13 years) and in adults: factor H (fH), factor I (fI), C4b-binding protein (C4 BP), properdin and vitronectin. We found that the concentrations of fH, fI, properdin and vitronectin in neonates are significantly lower than in adults. Remarkably, the concentration of C4 BP is below the method resolution (<50 micro g/ml) in 76% of the sera from neonates, while adults presented 199-532 microg/ml of C4 BP in their sera. The concentration of properdin in the sera from neonates and up to 1-year-old children was less than that observed in older children. Adults presented vitronectin levels significantly higher than all the other age groups in the study. No significant sex differences in the concentrations of all the studied regulatory proteins were detected. This study reveals the ontogeny of complement system in greater detail than previously available and may point to the reasons why neonates have higher susceptibility to develop life-threatening pyogenic infections. These reference values will be of use in clinical and laboratory investigations of disorders associated with low levels of these regulatory proteins.

Pancreatectomía distal con conservación de bazo: aspectos técnicos y análisis de nuestra casuística / Distal pancreatectomy with spleen preservation: technique and the outcomes of our experience

Antecedentes: Clásicamente la esplenectomía ha formado parte de la pancreatectomía distal. El reconocimiento de la importancia de las funciones del bazo ha motivado el interés en la conservación del mismo. La pancreatectomía distal con conservación de bazo fue descripta por primera vez en 1943. Con la excepción de algunos casos reportados en la literatura internacional, no se ha implementado rutinariamente en cirugía electiva. En los últimos años, se observó un interés en su utilización para el tratamiento de lesiones benignas y de bajo grado de malignidad y se desarrolló la resección por vía laparoscópica. Objetivo: Revisión de la evolución técnica y de nuestra casuística. Población: Intentamos conservar el bazo en 25 pacientes con lesiones benignas entre 1993 y 2001. Método: Se realizó pancreatectomía distal con conservación de bazo y vasos esplénicos. El último caso se realizó por vía laparoscópica. Resultados: La preservación del bazo fue posible en 24 de los 25 pacientes y en 23 pudieron preservarse los vasos esplénicos. El tiempo operatorio promedio fue 195 minutos. Cinco pacientes presentaron complicaciones postoperatorias (21,7 por ciento). No hemos observado isquemia ni absceso de bazo en ésta serie. La estadía hospitalaria promedio fue de 8,3 días. El seguimiento postoperatorio varió entre 5 y 80 meses (promedio 40 meses), sin detectarse alteraciones hematológicas por asplenia. Un paciente desarrolló diabetes insulino-dependiente 6 años luego de la operación (4 por ciento) y no se observó ningún caso de alteración de la función exocrina del páncreas. Conclusiones: La pancreatectomía distal con conservación de bazo es una operación segura y eficaz. La preservación de los vasos esplénicos evita el desarrollo de abscesos del bazo. La sección pancreática previa a la disección retrógrada, descripta en éste traabajo, facilita la preservación de los vasos esplénicos. Esta técnica es reproducible mediante el abordaje laparoscópico

Pancreatectomía distal con conservación de bazo: aspectos técnicos y análisis de nuestra casuística / Distal pancreatectomy with spleen preservation: technique and the outcomes of our experience

Antecedentes: Clásicamente la esplenectomía ha formado parte de la pancreatectomía distal. El reconocimiento de la importancia de las funciones del bazo ha motivado el interés en la conservación del mismo. La pancreatectomía distal con conservación de bazo fue descripta por primera vez en 1943. Con la excepción de algunos casos reportados en la literatura internacional, no se ha implementado rutinariamente en cirugía electiva. En los últimos años, se observó un interés en su utilización para el tratamiento de lesiones benignas y de bajo grado de malignidad y se desarrolló la resección por vía laparoscópica. Objetivo: Revisión de la evolución técnica y de nuestra casuística. Población: Intentamos conservar el bazo en 25 pacientes con lesiones benignas entre 1993 y 2001. Método: Se realizó pancreatectomía distal con conservación de bazo y vasos esplénicos. El último caso se realizó por vía laparoscópica. Resultados: La preservación del bazo fue posible en 24 de los 25 pacientes y en 23 pudieron preservarse los vasos esplénicos. El tiempo operatorio promedio fue 195 minutos. Cinco pacientes presentaron complicaciones postoperatorias (21,7 por ciento). No hemos observado isquemia ni absceso de bazo en ésta serie. La estadía hospitalaria promedio fue de 8,3 días. El seguimiento postoperatorio varió entre 5 y 80 meses (promedio 40 meses), sin detectarse alteraciones hematológicas por asplenia. Un paciente desarrolló diabetes insulino-dependiente 6 años luego de la operación (4 por ciento) y no se observó ningún caso de alteración de la función exocrina del páncreas. Conclusiones: La pancreatectomía distal con conservación de bazo es una operación segura y eficaz. La preservación de los vasos esplénicos evita el desarrollo de abscesos del bazo. La sección pancreática previa a la disección retrógrada, descripta en éste traabajo, facilita la preservación de los vasos esplénicos. Esta técnica es reproducible mediante el abordaje laparoscópico (AU)

Complement factor I deficiency in a family with recurrent infections.

Factor I deficiency causes a permanent, uncontrolled activation of the alternative pathway resulting in an increased turnover of C3 and consumption of factor B, factor H and properdin. Factor I deficiency is clinically associated with recurrent bacterial infections already in early infancy, mainly affecting the upper and lower respiratory tract, or presenting as meningitis or septicemia. We here report on a Brazilian family (n = 9) with known consanguinity, where in 3/7 children, suffering from chronic otitis, meningitis, and respiratory infections, a complete factor I deficiency was recognized. One of the patients died after fulminant sepsis. Hemolytic activity of the alternative pathway was not detectable in the patients' sera due to decreased plasma concentrations of C3, factor B and properdin. As a consequence of factor I deficiency, C3b could not be metabolized with the result that no C3-derived split products (C3dg/C3d) were detectable in the patients' sera. In vitro reconstitution with purified factor I restored the regulatory function in the patients' sera with the subsequent cleavage of C3b to C3c and C3dg. Factor H levels were decreased in all patients' sera and found to be tightly complexed with C3b resulting in a modified electrophoretic mobility. Upon factor I reconstitution, factor H was released from C3b regaining its beta 1 electrophoretic mobility. Complement-mediated biological functions like opsonization of bacteria, chemotactic activity and phagocytosis in these patients were impaired. The parents (cousins, 2nd degree) and 3/4 siblings had significantly reduced factor I plasma levels without further alteration in their complement profile. 3 of these obviously heterozygously deficient family members suffered from recurrent bacterial infections of different frequency and severity.

Activity of the alternative pathway of complement in the newborn infant.

Levels of C3, properdin, factor B, and C3 to C9 activity were markedly reduced in cord sera taken from 94 normal newborn infants. Nevertheless, cord serum supported complete activation of its own alternative pathway by zymosan or CoF. Lysis of a target cell, however, was defective; nearly 75% of cord sera had reduced rabbit erythrocyte CH50 titers. These were partially increased by the addition of factor B and properdin, and totally restored by adding factor B, properdin, and C3 to C9. Therefore, although the alternative pathway of the neonate is intact, it appears to be limited in its ability to generate an adequate number of stable and active enzymatic sites on a target cell membrane.

Decreased opsonization for Streptococcus pneumoniae in sickle cell disease: studies on selected complement components and immunoglobulins.

Opsonic activity for Streptococcus pneumoniae in the sera of patients with sickle cell disease was reduced in comparison to the opsonic activity of sera from age-matched normal children. No difference in opsonic activity for Escherichi coli was observed in the sera from patients or normals. Total hemolytic complement, conversion of C3 by inulin and cobra venom factor, and levels of C3, factor B, properdin, C3b inactivator, and immunoglobulins G, A, and M were normal in patients' sera. The opsonic abnormality for S. pneumoniae was attributed to a deficiency of serum proteins rather than to an inhibitor of opsonic function. The data suggest that decreased opsonization was not associated with a deficiency of those complement components or immunoglobulins measured in this study.

Bf polymorphism: another variant (S0.8).

A "new" variant band in the Bf system has been found in the serum of three individuals belonging to a tribe of Brazilian Indians (Karaja--Bananal--Goias) and in the serum of a Caucasian individual from the area of Strasbourg. It is highly probable that the band represents another allele at the Bf locus BfS0.8.

Hereditary deficiency of the third component of complement in a child with fever, skin rash, and arthralgias: response to transfusion of whole blood.

A previously well 34-month-old male presenting with fever, skin rash, and arthralgias was found to lack C3 by immunochemical (undetectable) and hemolytic (1% normal) assays. No infectious agent could be demonstrated. Protein levels of Clq. C4, C5, properdin, and C3b-INA and hemolytic activities of complement components C1 to C9 except C3 were normal or elevated; total hemolytic complement activity was 13% of normal and was reconstituted by purified C3. Properdin factor B was 702 (normal 175 to 275) mug/ml, and was not cleaver upon addition of zymosan or cobra venom factor. The serum had normal immune adherence activity, but was deficient in ability to opsonize Candida albicans for uptake and Escherichia coli for killing by neurophils, generate neutrophil chemotactic factors and inhibit the growth of E. coli; these activities were restored by purified C3. A transfusion of 320 ml 1-hour-old normal whole blood on the fifty-second day resulted in transitory elevation of the C3 level to 25 mg/dl with a fall-off (approximately 2 1/2% per hour) to undetectable levels by 69 hours; it was followed by disappearance of the skin rash and arthralgias and return to normal of the previously elevated temperature and CRP levels. C3 levels in family members (seven of 24 half-normal), lack of anti-C3 activity, normal C3b-INA levels and a normal rate of catabolism of transfused C3 indicated that the deficiency was inherited with autosomal codominance and involved decreased synthesis of C3. Thus, this child is a unique individual with inherited C3 deficiency presenting with absence of repeated infections, whose symptoms of fever, skin rash, and arthralgia were abated by whole blood transfusion.

Interaction of E. coli strains with human serum: lack of relationship to K1 antigen.

Twenty-eight strains of E. coli isolated from infants were compared with respect to opsonic requirements, sensitivity to serum, and ability to activate serum chemotactic factors. Six of the strains were isolated from stools of healthy newborn infants; 22 were isolated from the cerebrospinal fluid or blood of infants with meningitis and/or septicemia. Eighteen of the strains had K1 polysaccharide antigen. Fourteen of the strains (seven with K1 antigen) activated complement via the alternative pathway and all of these strains were well opsonized in 4% pooled human serum. A higher concentration of serum was necessary to opsonize 12 of the 14 strains that did not activate the alternative pathway. A wide variation was also found in opsonic requirements of E. coli strains isolated from healthy and sick infants. There was no relationship of the K1 antigen to opsonic requirements, to capacity to activate complement via the alternative pathway, to generation of chemotactic factors, or to sensitivity to serum cidal activity. Therefore, the association of E. coli with K1 antigen and neonatal meningitis did not appear to be related to these bacteria-serum interactions.