Cutaneous manifestations of complement deficiencies.

In this review we address the main cutaneous manifestations and diseases associated with deficiencies in components of the complement system. The first part is devoted to hereditary angioedema, in which acute, sometimes life-threatening recurrent attacks of acute swelling, usually associated with gastrointestinal symptoms, occur. It is related to a structural or functional deficiency of C1 esterase inhibitor. Patients usually have lowered C4 levels, and diagnosis relies on determination of antigenic and/or functional C1 inhibitor level. The second part focuses on lupus erythematosus, as deficiencies in early components of the complement system, such as C1q, C1r, C1s, C2 or C4, are the strongest known disease susceptibility genes for the development of human systemic lupus erythematosus. Severe infections early in life and marked photosensitivity in a patient with lupus erythematosus are clues to an underlying complement deficiency. The genetic background and the clinical associations of the different components of the complement system will be detailed.

Molecular basis of complete complement C4 deficiency in two North-African families with systemic lupus erythematosus.

Complete deficiency of complement C4 is among the strongest genetic risk factors for human systemic lupus erythematosus (SLE). C4 is a constituent of the RP-C4-CYP21-TNX (RCCX) module in the human leukocyte antigen (HLA) that exhibits inter-individual copy-number and gene-size variations. Here, we studied two North-African families with complete C4 deficiency and SLE. The first included a Moroccan male SLE patient (1P) and a sibling, who were both homozygous for HLA-A*02 B*17 DRB1*07. The second had an Algerian female SLE patient (2P) homozygous for HLA-A*01 B*17 DRB1*13. Early SLE disease onset, the presence of photosensitive rashes, anti-Ro/SSA, renal disease and high titers of antinuclear antibodies were the common features of complete C4 deficiency. Southern blot analyses showed that 1P had monomodular RCCX with a long C4A, whereas 2P had bimodular RCCX with one long C4A and one short C4B. Genomic DNA fragments for these mutant genes were amplified and sequenced. A C>T transition that created the R540X nonsense mutation in C4A was found in 1P. An identical 4-bp insertion that generated the Y1537X nonsense mutation was discovered in both C4A and C4B of 2P. The high concordance of SLE and C4 deficiency among patients with non-DR3 and non-DR2 haplotypes underscores the importance of C4 proteins in the protection against SLE.

Formation of soluble immune complexes by complement in sera of patients with various hypocomplementemic states. Difference between inhibition of immune precipitation and solubilization.

To examine whether the ability of complement to form soluble immune complexes plays a role in preventing immune complex-mediated diseases, we analyzed the capacity of complement to inhibit immune precipitation (IIP) and to solubilize preformed immune aggregates (SOL) in 23 sera of patients with various hypocomplementemic states, and we correlated the results of these studies with the clinical syndromes found in the various patients. In sera with deficiency or depletion of early classical pathway components, IIP was profoundly altered, whereas SOL was delayed but in the normal range. In contrast, in sera with C3 depletion but intact classical pathway and in properdin-deficient serum, IIP was initially preserved, whereas SOL was abolished. Since the incidence of immune complex diseases in various hypocomplementemic states correlates with the severity of IIP defects, but not with reduced SOL, it is suggested that IIP is an essential biological function of complement that prevents the rapid formation of insoluble immune complexes in vivo.

Rearrangements and point mutations of P450c21 genes are distinguished by five restriction endonuclease haplotypes identified by a new probing strategy in 57 families with congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is caused by disorders of the P450c21B gene, which, with the P450c21A pseudogene, lies in the HLA locus on chromosome 6. The near identity of nucleotide sequences and endonuclease cleavage sites in these A and B loci makes genetic analysis of this disease difficult. We used a genomic DNA probe that detects the P450c21 genes (A pseudogene, 3.2 kb; B gene, 3.7 kb in Taq I digests) and the 3' flanking DNA not detected with cDNA probes (A pseudogene, 2.4 kb; B gene, 2.5 kb) to examine Southern blots of genomic DNA from 68 patients and 165 unaffected family members in 57 families with CAH. Of 116 CAH-bearing chromosomes, 114 could be sorted into five easily distinguished haplotypes based on blots of DNA digested with Taq I and Bgl II. Haplotype I (76 of 116, 65.6%) was indistinguishable from normal and therefore bore very small lesions, presumably point mutations. Haplotype II (4 of 116, 3.4%) and haplotype III (8 of 116, 6.9%) had deletions and duplications of the P450c21A pseudogene but had structurally intact P450c21B genes presumably bearing point mutations; point mutation thus was the genetic defect in 88 of 116 chromosomes (75.9%). Haplotypes IV and V lack the 3.7-kb Taq I band normally associated with the P450c21B gene. Haplotype IV (13 of 116, 11.2%) retains all other bands, indicating that the P450c21B gene has undergone a gene conversion event, so that it is now also associated with a 3.2-kb band. Haplotype V (13 of 116, 11.2%) lacks the 2.4-kb Taq I fragment and the 12-kb Bgl II fragments normally associated with the P450c21A pseudogene, as well as lacking the 3.7-kb Taq I fragment, indicating deletion of approximately 30 kb of DNA, resulting in a single hybrid P450c21A/B gene. Most (114 of 116, 98%) CAH alleles thus can easily be classified with this new probing strategy, eliminating many ambiguities resulting from probing with cDNA.

Pou-2--a zebrafish gene active during cleavage stages and in the early hindbrain.

We have cloned the zebrafish pou-2 gene which encodes a novel type (class VII) of POU domain. Maternal pou-2 transcripts are initially found in all blastomeres. However, during later cleavage stages pou-2 expression disappears in the marginal cells. Some of their progeny will form the first lineage restricted compartment during zebrafish development. Blastula pou-2 expression in confined exclusively to the deep embryonic layer (DEL) forming the embryo proper. No expression is found in extraembryonic tissues, i.e. the yolk syncytial layer (YSL) and the enveloping layer (EVL). Thus pou-2 expression during early embryogenesis correlates with the continuing absence of cell lineage restriction. Towards the end of gastrulation, pou-2 expression becomes confined to the neural plate, predominantly to the prospective hindbrain and to the spinal cord. pou-2 expression in the forming hindbrain is restricted to future rhombomeres r2 and r4. Retinoic acid treatment during epiboly alters the hindbrain domains of pou-2, suggesting that the entire anterior hindbrain acquires r4-like properties. This finding is supported by analysis of early pax-2 and krx-20 expression patterns in RA-treated zebrafish embryos. The changes resemble similar hindbrain transformations observed in other vertebrates, supporting an evolutionary conservation of the mechanisms segmenting the hindbrain of vertebrates. pou-2 appears to respond to the same signals as other presumed patterning genes. This observation, together with pou-2 expression in the hindbrain prior to morphological segmentation, suggests an important role for this putative transcription factor in establishing and specifying rhombomeric segments.

Regulatory gene expression patterns reveal transverse and longitudinal subdivisions of the embryonic zebrafish forebrain.

To shed light on the organization of the rostral embryonic brain of a lower vertebrate, we have directly compared the expression patterns of dlx, fgf, hh, hlx, otx, pax, POU, winged helix and wnt gene family members in the fore- and midbrain of the zebrafish. We show that the analyzed genes are expressed in distinct transverse and longitudinal domains and share expression boundaries at stereotypic positions within the fore- and midbrain. Some of these shared expression boundaries coincide with morphological landmarks like the pathways of primary axon tracts. We identified a series of eight transverse diencephalic domains suggestive of neuromeric subdivisions within the rostral brain. In addition, we identified four molecularly distinct longitudinal subdivisions and provide evidence for a strong bending of the longitudinal rostral brain axis at the cephalic flexure. Our data suggest a strong conservation of early forebrain organization between lower and higher vertebrates.

Complement-mediated adherence of immune complexes to human erythrocytes. Difference in the requirements for C4A and C4B.

The classical pathway of complement is required for the adherence of soluble tetanus toxoid (TT)-human anti-TT complexes to erythrocytes. Using human C4-deficient serum we compared the capacity of the two forms of human C4 (C4A and C4B) to mediate this function: C4A was shown to be 1.5-fold more efficient than C4B. In contrast, haemolysis by C4B was 3.7-fold more efficient than by C4A. Such large differences suggest that both forms are complementary, and that C4A is preferentially involved in the processing of immune complexes in humans.

Heterogeneity in the structural basis of the human complement C4A null allele (C4A Q0) as revealed by HindIII restriction fragment length polymorphism analysis.

The highly polymorphic fourth component of human complement (C4) is usually encoded by two genes. C4A and C4B, adjacent to the 21-hydroxylase (21-OH) genes, 21-OHA and 21-OHB, and is also remarkable in the high frequency of the 'null' alleles, C4A Q0 and C4B Q0. The molecular basis for the C4A Q0 allele was studied in 26 families through restriction fragment length polymorphism (RFLP) analysis with C4 and 21-OH cDNA probes after digestion of the DNA with the endonuclease HindIII. The individuals expressing the extended haplotype HLA-A1 (of A2) Cw7 B8 C2C BfS C4AQ0B1 DR3 have a large deletion taking off the C4A and 21-OHA genes.

Genetic deficiency of C4 presenting with recurrent infections and a SLE-like disease. Genetic and immunologic studies.

A young girl presenting with recurrent pulmonary infections and atypical lupus erythematosus was totally deficient in C4. In one sister, also deficient in C4, the same symptoms developed. Results of family studies were consistent with an autosomal recessive mode of transmission and with linkage of the genes determining C4 deficiency to those of the major histocompatibility complex. The patient's serum and red cells were Chido- and Rodgers-negative. Humoral and cellular immunity were normal, except for a low lymphocyte response in mixed lymphocyte culture. The cellular function of the patient's polymorphonuclear leukocytes was normal, for both phagocytosis and bactericidal activity using Candida albicans. However, in the presence of C4-deficient serum, opsonin generation and bactericidal indexes were diminished. These defects were completely reversible upon addition of purified C4.

DNA methylation and the origin of complement factor B polymorphism.

BF is a polymorphic complement component encoded in the MHC. In each of two frequent alleles of BF, BF*FA and BF*FB, the difference in relation to the major allele BF*S has been shown to consist in the nonsynonymous substitution of only one base of the coding sequence. Both substitutions occur within the same codon and affect contiguous positions, corresponding to the dinucleotide CpG in BF*S. We propose here that BF*FA and BF*FB arose independently from BF*S by the frequently described transition mutations associated with cytosine methylation at CpG sites. By probing sperm DNA with methylation-sensitive restriction enzymes, we obtained experimental evidence of germ line methylation of the CpG site considered. The dinucleotide of the BF gene probably constitutes a site for recurrent mutation, and this is of relevance for the use of BF as a genetic marker, and the origin of forms of the protein with altered functional properties.

Human factor B. Complete cDNA sequence of the BF*S allele.

The gene of human complement factor B (BF) is located within the class III region of the major histocompatibility complex. The knowledge of the coding sequence of the BF gene rests on a set of partial sequence studies reported by various sources, and full-length sequences ascribed to specific alleles of this polymorphic complement component have not yet been published. Now, we have isolated and sequenced a collection of cDNA clones derived from BF*S, the major BF allele. We present an uninterrupted, allele-specific sequence of the entire coding region and the 3' untranslated segment of the cDNA. Extensive comparison of this and previously available sequence data was carried out, and a number of base substitutions were observed in relation to some of the earlier sequences. The possibility that these differences arise from polymorphism in the BF gene is discussed.

Molecular basis of complete C4 deficiency. A study of three patients.

The highly polymorphic fourth component of human complement (C4) is usually encoded by two genes, C4A and C4B, adjacent to the 21-hydroxylase (21-OH) genes and is also remarkable by the high frequency of the null alleles, C4A*Q0 and C4B*Q0. Complete C4 deficiency is exceptional because this condition appears only in homozygotes for the very rare double-null haplotype C4AQ0,BQ0. This condition in most cases gives rise to systemic lupus erythematosus and an increased susceptibility to infections. The molecular basis for complete C4 deficiency has not yet been established. Therefore we studied the DNA of three previously described C4 deficient patients belonging to unrelated families by restriction fragment length polymorphism analysis using C4 and 21-OH probes. These studies revealed a deletion of the C4B and 21-OHA genes in two patients and no deletion at all in the third patient. Therefore, complete C4 deficiency as a result of homozygosity for the C4AQ0, BQ0 haplotype is not a consequence of a deletion of the C4 genes. The molecular basis of this genetic abnormality is certainly very complex and may vary also from one case to another.

HLA and GM in insulin-dependent diabetes in the Netherlands: report on a combined multiplex family and population study.

This report deals with the genetic factors involved in insulin-dependent diabetes mellitus (IDD) in The Netherlands. Twenty-two Dutch multiplex families with IDD were typed for HLA-A, -B, -C, and -DR antigens, for BF, C2, C4, and GLO polymorphisms, as well as for GM allotypes of immunoglobulins. In addition, 53 unrelated IDD children and 31 unrelated patients with adult onset IDD were typed for HLA-A, -B, -C, and -DR antigens. A significant heterogeneity for the frequency of HLA-DR4 related to age of onset was observed. A significant deviation of the Hardy-Weinberg equilibrium was observed for the HLA-DR locus with an excess in patients of heterozygotes HLA-DR3, -DR4.HLA-B8, and HLA-B15 were not only secondary associated, but constituted with HLA-DR3 and -DR4, respectively, a haplotype in association with IDD. Nonrandom segregation of HLA-haplotypes was observed in multiplex families exemplified by an excess of HLA-identical affected sibpairs . Cross- overs between HLA-DR and GLO identified the HLA-DR segment as mainly involved in the association with IDD. Three diabetic haplotypes were confirmed to occur frequently among affected sibs: (a) A1, B8, BFS, C2.1, C4AQO , C4B1 ,DR3, GLO2 ; (b) Aw30, Cw5 ,B18,BFF1,C2.1, C4A3 , C4BQO ,DR3, GLO2 ; (c) A2,Cw3, B15,BFS, C2.1, C4A3 , C4B3 , DR4,GLO1. The segregation of GM allotypes to affected sibpairs was not significantly different from random segregation. The main conclusions from this study are that significant heterogeneity for age of onset exists and that the data are not compatible with simple genetic models including dominant, recessive, and intermediate models of inheritance. The data do require more complex models, involving two different HLA-linked (sets of) susceptibility genes.

Synthesis and regulation of complement components by human monocytes/macrophages and by acute monocytic leukemia.

Proteins of the complement system (C2, C3) are synthesized by human monocytes and macrophages, thus providing an important local source of these proteins in vivo which serve as a first-line host defense mechanism. In this study, we investigated the production of complement components C2, C4, and C9 by human monocytes/macrophages and by the pathologic cells of acute monocytic leukemia which represent a source of immature monocytic precursors. Human blood monocytes were collected and purified by cytapheresis and elutriation and leukemic cells by Ficoll gradient. Secretion of complement components was measured by a hemolytic assay. The evaluation of the mRNAs of the various complement components in the cells was performed by polymerase chain reaction (PCR) by adding 32P labeled deoxycytidinetriphosphate (dCTP) to the amplification step. Functional C2 was found to increase during in vitro maturation of macrophages up to the fourth week of culture. C2 mRNA was detected after amplification and increased during the maturation. Interferon-gamma (IFN-gamma) mediated a marked increase of the C2 mRNA. We found a decrease in synthesis of C4 mRNA during in vitro differentiation of human monocytes. The effect of IFN-gamma resulted in an increase in C4 mRNA. C9 mRNA was not detected although it was detected in the HepG2 hepatoma-derived cell line. Functional C2 was not detected by leukemic cells after 24 h of culture but little functional C4 was present in the cell supernatants. As they were by human monocytes and macrophages, C2 and C4 mRNAs were detected after amplification but C9 mRNAs were not detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Lupus erythematosus panniculitis with partial genetic deficiency of C2 and C4 in a child.

A 7-year-old girl developed recurrent febrile nodules and subcutaneous plaques on her arm, shoulder, and face. Primary acquired toxoplasmosis was diagnosed at onset, because of associated lymphadenopathy and detection of specific IgM. Skin lesions were responsive to therapy with systemic steroids but progressed to atrophy and poikiloderma within a few months. Subsequently, chloroquine therapy has been instituted and no relapse has occurred. Histopathologic findings and direct immunofluorescence studies were diagnostic of lupus erythematosus panniculitis. Electron microscopy showed lamellar inclusions within mast cells. Results of laboratory investigations disclosed leukopenia and hypocomplementemia with low C2 serum levels. A family study of the complement system, including C4 and Bf phenotyping and HLA A, B, and DR haplotyping, revealed the carriage of both C2 and C4A null alleles in the propositus. This observation suggests an additional link between lupus erythematosus panniculitis and the remainder of the lupus erythematosus clinical spectrum.

Lupus erythematosus associated with genetically determined deficiency of the second component of the complement.

BACKGROUND: The gene deletion responsible for the type I human complement C2 deficiency was reported in 1992. The purpose of our study is to evaluate clinical and immunological characteristics of 11 patients with lupus erythematosus and type I C2 deficiency. OBSERVATIONS: We observed 5 patients with a homozygous C2 deficiency and 6 with a heterozygous C2 deficiency. Eight patients had systemic lupus erythematosus, 2 had subacute cutaneous lupus erythematosus, and 1 had chronic lupus erythematosus. Photosensitivity was present in 73% of the patients, and 64% tested positive for anti-Ro (SSA) antibodies. Renal involvement that required immunosuppressive therapy was present in 54% of the patients. Ninety percent of the patients tested positive for antinuclear antibodies, and 54% tested positive for anti-double-stranded DNA antibodies. Phenotyping of the fourth component of the complement was performed in 82% of the patients and showed a C4A4B2 phenotype, which is suggestive for the type I C2 deficiency. CONCLUSIONS: Most patients with lupus erythematosus associated with C2 type I deficiency are photosensitive, and this is probably related to the presence of anti-Ro (SSA) autoantibodies. The prognosis for those patients is not better than that for patients with lupus erythematosus in general.

Interstitial laser hyperthermia model development for minimally invasive therapy of breast carcinoma.

BACKGROUND: This investigation describes the preclinical development of a laser fiberoptic interstitial delivery system for the thermal destruction of small breast cancers. We propose adaptation of this technology to stereotactic mammographic instrumentation currently employed for diagnostic core biopsy to thermally ablate a site of disease with maximal treatment efficacy, minimal observable superficial change, reduced patient trauma, and lowered overall treatment costs. STUDY DESIGN: Laser hyperthermia is a clinical modality that seeks to achieve tumor destruction through controlled tissue heating. The advantage of laser-induced hyperthermia over traditionally used heat sources such as ultrasound, microwave, or radiowave radiation lies in the ability to focus heat localization to the specific tumor tissue site. Neodymium:yttrium aluminum garnet (Nd:YAG) laser light transmitted through a fiberoptic cable to a diffusing quartz tip can induce such temperature increases leading to localized tissue destruction. Because breast cancer occurs with greatest frequency in the mature woman whose breast tissue has undergone glandular involution with fatty replacement, this study concentrates on determining the resultant laser energy heat distribution within fat and fibrofatty tissue. This investigation studied the time-temperature responses of ex vivo human breast and porcine fibrofatty tissue, which led to an in vivo subcutaneous porcine model for the practical demonstration of a laser hyperthermia treatment of small volumes of porcine mammary chain tissue. RESULTS: Spatial recordings of the resultant temperature fields through time exhibited similar, reproducible thermal profiles in both ex vivo human breast and subcutaneous porcine fat. In vivo laser-produced temperature fields in porcine subcutaneous fat were comparable to those in the ex vivo analyses, and showed a histologically, sharply defined, and controllable volume of necrosis with no injury to adjacent tissues or to overlying skin. CONCLUSIONS: Interstitially placed, fiberoptically delivered Nd:YAG laser energy is capable of controlled tissue denaturation to a defined volume for the treatment of small breast cancers. It is hoped that this minimally invasive approach, with further investigation and refinement, may lead to the effective treatment of small, well-defined breast cancers that are commonly diagnosed through stereographic mammography and stereotactic core biopsy. The juxtaposition of such a localized treatment modality with these increasingly used diagnostic tools is of considerable promise.

Post-traumatic pleural effusion: demonstration of local complement consumption.

The present case report describes a 27-year-old patient who presented with post-traumatic pleural effusion. Analysis of the pleural fluid showed hypereosinophilia (990 mm-3), a decreased level of total complement, and decreased levels of C3 and C4 fractions (less than 50% of normal serum levels), indicating a local consumption mechanism for complement. Complement serum levels (CH50, C3, C4) were normal. All other aetiologic possibilities were eliminated. This case suggests that the immunopathological mechanism of post-traumatic pleural effusion may involve activation of the classical pathway of complement and a recruitment of inflammatory cells such as eosinophils.

Laser application for minimal invasive reduction of thyroid gland tissue.

PURPOSE: Administration of antithyroid agents, surgery and radioiodine therapy are the established methods for treating hyperthyroidism. All of the methods are relatively complex and are associated with risks. That is why the sonographically controlled minimum invasive alcohol injection method was developed. The disadvantage associated with this procedure, however, is that it can not be controlled as effectively. METHODS: Thyroid gland tissue is removed from an animal model with delimitation by means of thermal coagulation using a new, specially developed ITT laser probe. The treatment is effected by puncturing intact skin. Placing of the probe is controlled sonographically. The puncture channel is 18 G; the laser probe has a diameter of 0.8 mm. The procedure is effected using local anesthesia which may be combined with light analgesic sedation and takes approx. 10 minutes. The laser application lasts 145 seconds and has a total power of 1195 joules. RESULTS: Laser treatment can be compared with the invasiveness of a jugular vein catheter unit and has good tolerance. Complete histologic healing of the coagulation zone takes 4 weeks and the boundaries of the scar contraction are barely recognizable. The size of the coagulation zone can only be controlled to a certain degree in the animal model on account of its anatomy. CONCLUSIONS: The minimal invasive method based on laser-induced reduction of thyroid gland tissue can be performed on an animal model and is safe. Further research needs to be done to determine the extent to which the results can be transferred to human beings.

[Changes in the polymorphism and concentrations of components of the class II complement after orthotopic transplantation of the liver]. / Evolution du polymorphisme et des concentrations des composants du complément de classe III après transplantation orthotopique du foie.

OBJECTIVES AND METHODS: The genes of complement factor B, C2 and C4 are located within the major histocompatibility complex class III region on chromosome 6 in man. These components demonstrate a genetic polymorphism which, when determinated, can be used to define complotypes (association of C2, factor B, C4A and C4B allotypes). On the other hand the liver is the main source of the circulating complement component synthesis. The aim of this study was to analyse the kinetics of several complement component (C3, factor B and C4) concentrations in the plasma and to assess changes in the polymorphic pattern of the complotypes after orthotopic liver transplantation. Nephelometry was used for plasma level measurements and factor B, C2 and C4 typings were performed with high voltage electrophoresis or isofocalisation and immunofixation at intervals before, during and after orthotopic liver transplantation in eleven patients. RESULTS: Complotypes changes were observed 24 hours after liver transplantation in all patients. A slight decrease in C3, C4, and factor B plasma levels was observed in the first hours after transplantation. A rapid increase in the levels of these components was observed subsequently, with normalization in less than 15 days. CONCLUSION: These results demonstrate a rapid synthesis of complement components and the changes in complement polymorphic patterns after liver transplantation.