George Füst

HIV transmission from female to male at improperly protected sexual intercourse

There is growing evidence that human immunodeficiency virus (HIV) infection can be transmitted from female to male after only 2 sexual contacts. The authors present a case in which the wife was infected with HIV in March 1986 as a result of transfusion of blood from a homosexual. She tested positive for HIV in January 1987 and in February was notified of her positive test result. The couple had had regular unprotected sexual intercourse between April 1986 and February 1987. In February 1987 the patients husband was negative for HIV infection and condom use was initiated. By October 1987 the husband was found to be seropositive for HIV. The couple reported that the condom had torn on several occasions since protected intercourse was initiated. It cannot be determined whether HIV was transmitted before February during unprotected intercourse and the husband seroconverted after the 1st blood sampling or whether HIV was transmitted after notification of the wifes seropositive status.

Independent and Joint Effects of Antibodies to Human Heat-Shock Protein 60 and Chlamydia pneumoniae Infection in the Development of Coronary Atherosclerosis

BackgroundStudies have suggested that the prevalence of antibodies against heat-shock proteins (HSPs), Chlamydia pneumoniae (Cpn), and cytomegalovirus (CMV) is associated with coronary artery disease (CAD), but the independent or joint effects of human (h) HSP60 antibodies and these pathogens in patients have not been fully elucidated. Methods and ResultsA total of 405 subjects (276 patients with CAD and 129 control individuals) were tested for serum antibodies to hHSP60, Cpn, and CMV immediate-early-1 (IE1) antigens. Patients were also assessed for serum cholesterol, triglyceride levels, and smoking habit. Significantly elevated levels of antibodies to hHSP60 and Cpn but not to CMV-IE1 antigens were documented in CAD patients. Multiple logistic regression analysis and subanalyses of selected subjects showed that these associations were independent of age, sex, smoking, and serum lipid levels. Antibodies to hHSP60 and Cpn did not correlate quantitatively; however, the relative risk of disease development was substantially increased in subjects with high antibody levels to both hHSP60 and Cpn, reaching an odds ratio of 82.0 (95% CI 10.6 to 625.0). ConclusionsHigh levels of antibodies to hHSP60 and Cpn are independent risk factors for coronary atherosclerosis, but their simultaneous presence substantially increases the risk for disease development.

Activation of the complement system in normal pregnancy and preeclampsia.

The purpose of this study was to explore the role of the complement system in normal human pregnancy and preeclampsia in a comprehensive manner, measuring circulating levels of complement proteins, their activation fragments and regulatory factors, as well as those of C-reactive protein (CRP). Sixty preeclamptic patients, 60 healthy pregnant women and 59 healthy non-pregnant women were involved in this case-control study. Circulating levels of complement components and CRP were determined with ELISA, radial immunodiffusion and particle enhanced immunoturbidimetric assay. Levels of CRP, C4d, C3a, SC5b9, C3, C9 and factor H antigen were significantly higher, while those of C1-inhibitor were significantly lower in healthy pregnant than non-pregnant women. In addition, preeclamptic patients had significantly higher CRP, C4d, C3a, SC5b9 levels and significantly lower C3 concentrations as compared to healthy pregnant women. Their CRP, C4d, C3a, SC5b9, C4, C3, C9 and factor H antigen levels were significantly higher, while C1-inhibitor concentrations were significantly lower compared with healthy non-pregnant women. However, no significant difference was found in Bb and C4b-binding protein levels among the three study groups. Preeclamptic patients with fetal growth restriction had significantly higher plasma SC5b9 levels than those without IUGR. There was a relative deficiency of C1-inhibitor and C4b-binding protein, and a relative abundance of factor H both in normal pregnancy and preeclampsia. Activation of the classical or lectin pathway (C4d) showed significant positive correlation to C3 activation (C3a) both in healthy pregnant women and preeclamptic patients. However, the correlation between C3 and terminal pathway activation was dominating only in patients with preeclampsia, but not in healthy pregnant women. In conclusion, the complement system is activated through the classical and/or lectin pathways with increased terminal complex formation in the third trimester of normal human pregnancy, and further in preeclampsia, as shown by the elevated amounts of activation markers in the systemic circulation. Excessive activation of the terminal pathway is associated with fetal growth restriction in preeclamptic women. However, additional studies are required to determine the cause and consequence of systemic complement activation in this pregnancy-specific disorder.

The role of C3 in the immune response

The complement system, particularly the third component, plays an important modulatory role in the inductive phase of the immune response. As discussed here by Anna Erdei and colleagues, the picture that is emerging is that immobilized C3 split products facilitate the cooperation between immunocompetent cells and are co-stimulatory molecules in T- and B-cell activation, probably as a result of their ability to promote cell-cell adhesion. In contrast, soluble C3 products inhibit lymphocyte proliferation.

Heat shock protein 70 is a potent activator of the human complement system

Abstract According to new hypotheses, extracellular heat shock proteins (Hsps) may represent an ancestral danger signal of cellular death or lysis-activating innate immunity. Recent studies demonstrating a dual role for Hsp70 as both a chaperone and cytokine, inducing potent proinflammatory response in human monocytes, provided support for the hypothesis that extracellular Hsp is a messenger of stress. Our previous work focused on the complement-activating ability of human Hsp60. We demonstrated that Hsp60 complexed with specific antibodies induces a strong classical pathway (CP) activation. Here, we show that another chaperone molecule also possesses complement-activating ability. Solid-phase enzyme-linked immunosorbent assay was applied for the experiments. Human Hsp70 activated the CP independently of antibodies. No complement activation was found in the case of human Hsp90. Our data further support the hypothesis that chaperones may messenger stress to other cells. Complement-like molecules and primitive immune cells appeared together early in evolution. A joint action of these arms of innate immunity in response to free chaperones, the most abundant cellular proteins displaying a stress signal, may further strengthen the effectiveness of immune reactions.

Real-time PCR quantification of human complement C4A and C4B genes

BackgroundThe fourth component of human complement (C4), an essential factor of the innate immunity, is represented as two isoforms (C4A and C4B) in the genome. Although these genes differ only in 5 nucleotides, the encoded C4A and C4B proteins are functionally different. Based on phenotypic determination, unbalanced production of C4A and C4B is associated with several diseases, such as systemic lupus erythematosus, type 1 diabetes, several autoimmune diseases, moreover with higher morbidity and mortality of myocardial infarction and increased susceptibility for bacterial infections. Despite of this major clinical relevance, only low throughput, time and labor intensive methods have been used so far for the quantification of C4A and C4B genes.ResultsA novel quantitative real-time PCR (qPCR) technique was developed for rapid and accurate quantification of the C4A and C4B genes applying a duplex, TaqMan based methodology. The reliable, single-step analysis provides the determination of the copy number of the C4A and C4B genes applying a wide range of DNA template concentration (0.3–300 ng genomic DNA). The developed qPCR was applied to determine C4A and C4B gene dosages in a healthy Hungarian population (N = 118). The obtained data were compared to the results of an earlier study of the same population. Moreover a set of 33 samples were analyzed by two independent methods. No significant difference was observed between the gene dosages determined by the employed techniques demonstrating the reliability of the novel qPCR methodology. A Microsoft Excel worksheet and a DOS executable are also provided for simple and automated evaluation of the measured data.ConclusionThis report describes a novel real-time PCR method for single-step quantification of C4A and C4B genes. The developed technique could facilitate studies investigating disease association of different C4 isotypes.

Association of Chlamydia pneumoniae with coronary artery disease and its progression is dependent on the modifying effect of mannose-binding lectin

Background—The possible association between coronary artery disease (CAD) and Chlamydia pneumoniae (C pneumoniae) infection is controversial. On the basis of the recent suggestion that mannose-binding lectin (MBL) variant alleles are related to an increased risk of severe atherosclerosis, and on the in vitro interaction of MBL with C pneumoniae, we asked whether MBL might contribute to CAD in conjunction with C pneumoniae. Methods and Results—Antibodies to C pneumoniae were measured by immunofluorescence and MBL alleles were determined by polymerase chain reaction technique in samples from 210 patients with CAD and 257 healthy subjects from Hungary collected between 1995 and 1996. A higher percentage of patients with CAD were anti-C pneumoniae positive as compared with the control group (P =0.058). However, at logistic regression analysis adjusted to age, sex, and serum lipid levels, this difference was confined only to subjects carrying MBL variant alleles (P =0.035, odds ratio 2.63, [95% CI: 1.07 to 6.45]). In contrast, no significant difference was seen in those homozygous for the normal MBL allele (P =0.412). During a 65±5.8-month follow-up period, major outcomes (new myocardial infarction, and/or bypass operation or cardiovascular death) occurred in 11 C pneumoniae positive and 3 C pneumoniae negative patients. In the C pneumoniae positive group, the odds ratio of development of outcomes was 3.27 (95% CI: 1.10 to 9.71, P =0.033) in the carriers of the MBL variant alleles compared with the homozygous carriers of the normal MBL allele. Conclusions—These results indicate that infection with C pneumoniae leads mainly to the development and progression of severe CAD in patients with variation in the MBL gene.

Diversity in Intrinsic Strengths of the Human Complement System: Serum C4 Protein Concentrations Correlate with C4 Gene Size and Polygenic Variations, Hemolytic Activities, and Body Mass Index

Among the genes and proteins of the human immune system, complement component C4 is extraordinary in its frequent germline variation in the size and number of genes. Definitive genotypic and phenotypic analyses were performed on a central European population to determine the C4 polygenic and gene size variations and their relationships with serum C4A and C4B protein concentrations and hemolytic activities. In a study population of 128 healthy subjects, the number of C4 genes present in a diploid genome varied between two to five, and 77.4% of the C4 genes belonged to the long form that contains the endogenous retrovirus HERV-K(C4). Intriguingly, higher C4 serum protein levels and higher C4 hemolytic activities were often detected in subjects with short C4 genes than those with long genes only, suggesting a negative epistatic effect of HERV-K(C4) on the expression of C4 proteins. Also, the body mass index appeared to affect the C4 serum levels, particularly in the individuals with medium or high C4 gene dosages, a phenomenon that was dissimilar in several aspects from the established correlation between body mass index and serum C3. As expected, there were strong, positive correlations between total C4 gene dosage and serum C4 protein concentrations, and between serum C4 protein concentrations and C4 hemolytic activities. There were also good correlations between the number of long genes with serum levels of C4A, and the number of short genes with serum levels of C4B. Thus, the polygenic and gene size variations of C4A and C4B contribute to the quantitative traits of C4 with a wide range of serum protein levels and hemolytic activities, and consequently the power of the innate defense system.

Studies on the interactions between C-reactive protein and complement proteins

Several studies have investigated the interactions between C‐reactive protein (CRP) and various complement proteins but none of them took into consideration the different structural forms of CRP. The aim of our study was to investigate whether the different antigenic forms of CRP are able to bind C1q, to trigger activation of the C1 complex and to study the ability of the various CRP forms to bind complement factor H (FH) and C4b‐binding protein (C4BP). Interactions between various CRP forms and complement proteins were analysed in enzyme‐linked immunosorbent assay and surface plasmon resonance tests and activation of the C1 complex was followed in a reconstituted system using purified C1q, C1r and C1s in the presence of C1‐INH. Native, ligand‐unbound CRP activated the classical pathway weakly. After binding to phosphocholine, native CRP bound C1q and significantly activated C1. Native CRP complexed to phosphocholine did not bind the complement regulatory proteins FH and C4BP. After disruption of the pentameric structure of CRP, as achieved by urea‐treatment or by site‐directed mutagenesis, C1q binding and C1 activation further increased and the ability of CRP to bind complement regulatory proteins was revealed. C1q binds to CRP through its globular head domain. The binding sites on CRP for FH and C4BP seemed to be different from that of C1q. In conclusion, in parallel with the increase in the C1‐activating ability of different CRP structural variants, the affinity for complement regulatory proteins also increased, providing the biological basis for limitation of excess complement activation.

Defensins purified from human granulocytes bind C1q and activate the classical complement pathway like the transmembrane glycoprotein gp41 of HIV-1.

The transmembrane glycoprotein gp41 of HIV-1 contains a C1q binding domain (HIVenv 583-610) and activates the human complement system through the classical pathway. Based on structural and functional similarities between human defensins (human neutrophil peptide, HNP 1-3) and synthetic peptides representing the env 583-610 region of HIV-1, we found it interesting to investigate the C1q binding and complement activating ability of human defensins. Human defensins were purified and characterized by size exclusion chromatography, ultrafiltration, gel electrophoresis and HPLC. The complement activating ability of the purified peptides was assessed in a solid-phase immunoassay. Defensins, fixed to an ELISA plate, were able to bind the C1q subcomponent of the first complement component (C1), triggering the classical pathway of complement activation which led to C4b binding to the plate. Reduction and subsequent alkylation of disulfide bridges of defensins greatly decreased the C1q binding ability but complement activation (C4b binding) remained high. Further acetylation of the reduced defensin peptide resulted in a molecule which bound very little or no C1q but still activated the complement cascade. These phenomena indicate that defensins interact with the complement system via C1q-dependent and C1q-independent mechanisms, and extend the number of functional similarities between defensins and gp41 of HIV-1 to include C1q binding and complement activation.