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PubMed1989

Familial properdin deficiency associated with chronic discoid lupus erythematosus.

A large family comprised of 18 members is described. Four male members are properdin-deficient, all are healthy bar the index patient who presented with chronic discoid lupus erythematosus. Serum from properdin-deficient males had a reduced ability to lyse rabbit erythrocytes via the alternative pathway or solubilize pre-formed immune complexes. Addition of purified properdin restored these activities. Classical pathway activity was normal. Definite, probable and possible female carriers had normal classical and alternative pathway activities.

Family↗
PubMed1977

Activation of the classical and properdin pathways of complement by bacterial lipopolysaccharides (LPS).

Bacterial lipopolysaccharides (LPS) have been demonstrated to activate both the classical and the properdin pathways of complement. The lipid A region of the LPS is responsible for classical pathway activation and the polysaccharide region responsible for properdin pathway activation. Classical pathway activation by lipid A does not depend upon antibody to the lipid A and properdin pathway activation proceeds by a lipid A-independent mechanism. The polysaccharide portion of the LPS molecule exerts a modifying influence on the potential anticomplementary activity of the lipid A.

Complement System Proteins↗
PubMed1978

[Properdin in the lymph in traumatic stress].

The changes of properdin level in different kinds of lymph and blood of dogs in case of burn of hind paws (the 1st group), and of craniocerebral injury (the 2nd group) were investigated. The properdin level proved to increase in the lymph of the cervical duct and the afferent lymph of the popliteal node in both the groups of dogs. The properdin level in the afferent lymph of the popliteal lymph node, thoracic duct and in blood was reduced in case of the burn and rose in cranicerebral injury. The total protein level in the afferent and efferent lymph of the popliteal lymph node, the cervical and thoracic ducts rose, whereas the total blood protein level fell.

Animals↗
PubMed1982

Investigations on properdin activity in the mature and premature newborns with the intrauterine infection.

Properdin level was determined in amniotic fluid, venous blood serum of mothers, umbilical cord blood serum and venous blood of 4-day-old newborns infected intrauterinally. Investigations were performed in 30 babies born at term and 15 premature babies born in the 31st-37th weeks of pregnancy. The control group comprised 30 mature and 15 premature healthy babies. It was observed that among the mature as well as premature infants, in the cases of the intrauterine infections properdin level, was significantly higher in venous blood serum of mothers and venous blood of 4-day-old infants. However, no significant changes in properdin level in umbilical cord blood were noted.

Amniotic Fluid↗
PubMed1979

Modulation of the properdin amplification loop in membranoproliferative and other forms of glomerulonephritis.

The mean serum concentrations of C3b inactivator (C3bINA) and beta1H globulin were measured in eighty-six sera (thirty-five membranoproliferative, thirteen membranous, thirty-one focal and seven minimal change) taken from seventy-five patients with histologically diagnosed glomerulonephritis. In none of the four groups of sera did the mean concentrations of both these proteins differ significantly from the mean levels in a group of fifty normal sera. However, in the membranoproliferative group, the mean level of C3bINA, but not beta1H, was significantly lower in the nephritic factor positive than in the nephritic factor negative group. When the eighty-six sera were considered together, serum concentrations of C3bINA and beta1H correlated with levels of C3, factor B, properdin and C4. When the membranoproliferative group was considered separately, C3bINA levels correlated with levels of C3, factor B, properdin and C4 and beta1H correlated with C3 and factor B, but not properdin or C4 in the nephritic factor negative group, but no such correlations were observed in the nephritic factor positive group. The significance of these findings is discussed in the light of current thoughts on the mechanisms of modulation of the alternative pathway.

Beta-Globulins↗
PubMed1977

Correlation between levels of breakdown products of C3, C4, and properdin factor B in synovial fluids from patients with rheumatoid arthritis.

Synovial fluids from 31 patients with seropositive rheumatoid arthritis (RA) and 23 patients with seronegative RA had significantly increased levels of breakdown products to C3, C4, and properdin factor B when compared to patients with osteoarthritis (OA) (P less than 0.01). The same patients exhibited a considerable overlap of native C3, C4, and properdin factor B levels when their results were compared with those of OA patients. The parallel increase of C3d, C4d, and Ba levels in patients with RA suggests an activation of the complement system rather than a nonspecific enzymatic breakdown in synovial fluids.

Arthritis, Rheumatoid↗
PubMed1994

The fractionation of human plasma proteins. I. Affinity purification of human complement properdin.

A method was developed for the affinity purification of human complement properdin. The preparation is part of an integrated scheme in which over 20 human plasma proteins can be recovered in a highly purified form. The yield of properdin was 5.9 mg from 3 liters of plasma, amounting to a 28% recovery. The crucial step in the purification was the application of affinity chromatography using C3b-ester-Sepharose.

Blood Proteins↗
PubMed1991

Membrane interaction of 'peptide P' derived from the repeating motif of properdin.

A 24 amino acid residue peptide corresponding to the central part of the 'thrombospondin-repeat' motif of the human serum protein properdin was synthesized. The peptide, termed 'peptide P', contains three tryptophans near the N-terminus and an arginine cluster close to the C-terminus. Its sequence closely matches a consensus sequence which has been claimed to characterize a sulfatide binding motif. Membrane binding of peptide P was analyzed using changes in its tryptophan emission upon adding small unilamellar vesicles. The peptide bound to the membranes in a way suggesting simple water/membrane partitioning. Analysis of electrostatic effects at different ionic strengths indicated small electrostatic contributions upon interaction with zwitterionic lipid, despite the large charge number (z = +4) of the peptide. Membrane affinity was increased by one order of magnitude if the bilayers contained 20% of negatively charged lipid. No difference could be detected whether the charged lipid was sulfatide or phosphatidylglycerol. Strong and rapid vesicle aggregation was evident as the peptide associated with the negatively charged vesicles. In addition, a fluorescent energy transfer assay with vesicles and internal total reflection fluorescence microscopy on supported bilayers were used to study membrane interaction of whole human properdin. No sulfatide specificity could be detected.

Amino Acid Sequence↗
PubMed1991

The properdin structural locus (Pfc) lies close to the locus for tissue inhibitor of metallothionine proteases (Timp) on the mouse X chromosome.

We have confirmed the assignment of the structural locus of the complement factor properdin (Pfc) to the mouse X chromosome and mapped it between monoamine oxidase-A (Mao-a) and hypoxanthine phosphoribosyltransferase (Hprt) using a Mus spretus x Mus musculus interspecific backcross of 108 animals. The structural locus for murine tissue inhibitor of metallothionine proteases (Timp) could not be separated from properdin in a panel of 18 recombinant animals. By minimizing the number of double recombinants the following gene order was obtained: Otc-Mao-a-(Pfc, Timp)-Hprt-Cf-9. The implications for comparative mapping of human and mouse X chromosomes are discussed.

Animals↗
PubMed1992

Physical linkage of the A-raf-1, properdin, synapsin I, and TIMP genes on the human and mouse X chromosomes.

Genes encoding the neuron-specific phosphoprotein synapsin I (SYN1), the glycoprotein tissue inhibitor of metalloproteinases (TIMP), the proto-oncogene A-raf-1 (ARAF1), and properdin (PFC), a positive regulator of the alternative pathway of human complement, lie within a conserved synteny encompassing the proximal short arm of the human X chromosome (Xp21.1-p11) and the centromeric end of the mouse X chromosome (A1-A5). We have used a mouse interspecific cross to demonstrate genetic linkage of Syn-1, Timp, and Araf and also show physical linkage, with Timp lying only 10 kb from Araf, within an intron of the Syn-1 gene. Detailed restriction mapping shows that Timp is transcribed in the same direction as Araf but in the opposite direction to the Syn-1 gene. Analysis of the corresponding region of the human X chromosome indicates a similar arrangement and in addition shows that the properdin gene lies within 5 kb of the 5' end of the synapsin I gene.

Animals↗
PubMed2000

Inhibition of complement alternative pathway function with anti-properdin monoclonal antibodies.

Complement activation products appear to contribute to the pathology of several acute and chronic inflammatory conditions. The relative contributions of the classical and alternative complement pathways to these pathologies have, in large part, been undefined. Considerable progress has been made recently in identifying inhibitors of complement activation and demonstrating that such molecules can attenuate inflammation in various models of disease. However, most of these complement inhibitors affect aspects of both the classical and alternative pathways. In an effort to better define the role of the alternative complement pathway in complement-mediated inflammatory conditions, we have developed monoclonal antibodies that specifically inhibit alternative pathway function. These blocking antibodies bind human properdin with high avidity and prevent its interaction with the alternative pathway C3 convertase. This results in a cessation of alternative pathway function in several in vitro assay systems. When tested in a model of cardiopulmonary bypass, in which human blood passes through tubing, a selected antiproperdin antibody caused nearly complete inhibition of the C3a and C5b-9 formation that was seen in untreated blood. Moreover, the anti-properdin agent resulted in a dramatic reduction of neutrophil and platelet activation in the bypass model. Surprisingly, the monoclonal antibody also caused a significant inhibition of C5b-9 generation when classical pathway activators, such as heparin-protamine or immune complexes, were added to human blood. These latter data suggest that the alternative pathway contributes significantly to the formation of complement activation products in blood when the classical pathway is initially triggered.

Antibodies, Monoclonal↗
PubMedDate not supplied

Localization of the properdin factor complement locus Pfc to band A3 on the mouse X chromosome.

The locus for properdin (properdin factor complement, Pfc), a plasma glycoprotein, has been mapped to band A3 of the mouse X chromosome by in situ hybridization to metaphase spreads containing an X;2 Robertsonian translocation. The X-linkage of the locus has also been confirmed by analysis of Mus musculus x Mus spretus interspecific crosses. The XA3 localization for Pfc places it in the chromosomal segment conserved between man and mouse which is known to contain at least six other homologous loci (Cybb, Otc, Syn-1 Maoa, Araf, Timp).

Animals↗
PubMed1972

Inactivator of the third component of complement as an inhibitor in the properdin pathway.

Evidence has been obtained that a single protein, known to modulate classical complement activation, also acts as an inhibitor in the properdin or alternate complement pathway. A highly purified inactivator of the third component of complement (C3) from human serum inhibited the proteolysis of Factor B in the properdin system (glycine-rich beta-glycoprotein) by glycine-rich beta-glycoproteinase. The inhibition was by the enzymatic destruction of glycine-rich beta-glycoproteinase activity. The major fragment of C3, C3b, which is the only known substrate of the C3 inactivator, blocked the destruction of glycine-rich beta-glycoproteinase by the C3 inactivator. Thus, in its inhibition of the porperdin pathway, the C3 inactivator destroys both the active form of glycine-rich beta-glycoproteinase and a protein involved in the conversion of the zymogen form of this enzyme (proglycine-rich beta-glycoproteinase) to its active form. The increased susceptibility to infections in a patient homozygous for deficiency of the C3 inactivator demonstrates the biologic significance of this protein.

Adult↗
PubMed2006

Properdin deficiency in a boy with fulminant meningococcal septic shock.

UNLABELLED: Bacterial meningitis is a rare presentation for congenital immunodeficiency, but meningococcal invasive diseases and meningitis have been associated with late complement component deficiencies and properdin deficiency. A 5-y-old boy of non-consanguineous parents was admitted to our hospital with meningococcal septic shock. He had previously been suffering from recurrent respiratory infections. His 13-y-old brother had also been treated for meningococcal meningitis when he was 7 y old. Immunological studies, done after recovery, on the patient and his two brothers revealed normal immunoglobulin, IgG subclasses, C3, C4 and CH50 levels. Haemolytic activity of the alternative complement pathway could not be detected, and properdin concentrations were <0.01 mg/l in serum samples from the patient and his brothers. The patient and family members received quadrivalent polysaccharide meningococcal vaccine. The patient was discharged on penicillin prophylaxis, and he remained healthy during the ensuing year. CONCLUSION: Our findings stress that measurement of the haemolytic activity of the alternative complement pathway in addition to classical pathway haemolytic complement activity should be performed in patients with meningococcal disease to reveal various forms of complement deficiency. This is particularly important when there is a family history, or recurrences or infection due to uncommon serogroups. Deficient individuals and affected family members might be protected from infection by vaccination.

Causality↗
PubMed1991

The properdin-like type I repeats of human thrombospondin contain a cell attachment site.

Thrombospondin (TS) is a modular adhesive glycoprotein that contains three domains previously implicated in the attachment of cells to TS. These include the amino-terminal heparin-binding domain, the carboxy terminal cell or platelet-binding domain, and an RGDA sequence of TS. We have characterized a mAb against human TS, designated A4.1, which inhibits the attachment of human melanoma cells (G361) to TS. The epitope for A4.1 lies within the amino terminal half of the central stalklike region of TS which is distinct from the three known cell attachment sites. This region of TS is recovered in a 50-kD peptide after chymotryptic digestion of TS in EDTA. It contains the procollagen-like domain of TS as well as three type I repeats of a 60-residue segment homologous to two malarial proteins and the complement proteins properdin, and factors C6 through C9. The purified chymotryptic fragment is an effective attachment factor for G361 cells. A4.1 blocks adhesion to the 50-kD domain, as do some sulfated glycoconjugates. RGD (and RGE) peptides and mAbs against other domains of TS are not inhibitory. Peptides (19 mers) based on the core homology sequence of the three type I repeats of TS are potent attachment factors for these cells, and this adhesion is also inhibited by sulfated glycoconjugates. A polyclonal antibody raised against one of these peptides inhibits adhesion of G361 cells to the peptides, to the 50-kD fragment and to intact TS. Thus a new cell-adhesion site has been identified in TS whose sequence is very similar to the site identified in region II of the circumsporozoite protein of malaria parasites (Rich, K. A., F. W. George IV, J. L. Law, and W. J. Martin. 1990. Science (Wash. DC) 249:1574-1577. Thus there may be a common receptor which binds TS, malarial proteins, and properdin.

Amino Acid Sequence↗
PubMed1974

The role of properdin in the alternate pathway of complement activation.

Properdin (P), a highly basic euglobulin, was purified from human serum to molecular homogeneity without the use of zymosan. Isolated P was found to efficiently initiate activation of the alternate pathway of complement activation (C3 activator or properdin system) and to be an essential component during its early reaction stages. The activity of isolated P did not require the presence of an activating polysaccharide. It was therefore concluded that purified P had been obtained in an activated form (P). In an isolated reaction system containing purified C3, C3 proactivator (C3PA), and C3 proactivator convertase (C3PAse), P was able to mediate the activation of C3PAse which in turn activated C3PA to cleave C3. This activation of C3PAse was found to depend on the presence of native C3. These results allowed the formulation of a concept in which P is envisaged to act as a modulator of native C3 enabling it to activate C3PAse. Activation of C3 was efficiently mediated by P in the fluid phase. Efficient activation of C5, however, required the participation of an insoluble polysaccharide (zymosan). The possibility is raised therefore that P might also be an integral part of the multimolecular C5 convertase of the alternate pathway of complement activation.

Animals↗
PubMed1992

Linkage analysis in properdin deficiency families: refined location in proximal Xp.

Properdin is a component of the alternative activation pathway of the complement system. Deficiency or dysfunction of the protein is inherited in an X-linked recessive manner. Affected males have an increased risk of developing meningococcal disease. Six multi-generation families with different types of properdin deficiency were analyzed using microsatellite and other polymorphisms on the X chromosome. Based on multipoint data, it was found that the disease gene maps close to DXS255 (Zmax = 13.3 at theta max = 0.00) and DXS426 (Zmax = 12.9 at theta max = 0.00) on the Xp-arm near the centromere. There was no indication of genetic heterogeneity among the six families analyzed. Thus it is now possible to perform accurate DNA-based determination of the inheritance of the mutation in affected families.

Chromosome Mapping↗
PubMed1987

Concentrations of C1q, factor B, factor D and properdin in healthy children, and the age-related presence of circulating C1r-C1s complexes.

The concentrations of C1q, factor B, factor D and properdin were determined in healthy children belonging to various age groups of one through five years of age. All concentrations were found to be age-dependent, though they varied from one component to another with regard to ontogenetic pattern. Thus, the concentrations of factor B were high, and those of factor D low throughout the age range studied. C1q and properdin levels were lowest in the younger children, who also showed a fairly high incidence of C1r-C1s complexes in excess of C1q. Since the concentrations of C1q are influenced by those of IgG, the presence of C1r-C1s complexes might partly have reflected maturation of immunoglobulin synthesis during ontogeny.

Age Factors↗