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PubMed1989

Detection of a high-affinity binding site for the globular head regions of the C1q complement protein on a human diploid fibroblast subtype.

A cultured fibroblast subtype with growth and synthetic properties expected of cells residing in healing wounds and in inflammatory lesions binds the Clq component of complement with a functional affinity much higher than that of the remaining cell population. In this study we examined the optimal conditions that favor the interaction between purified 125I-labeled Clq and this cell subtype, following its isolation from the parent culture using a cell sorter, and assessed the biologic consequences of binding. Binding of 125I-Clq to the cell surface is specific, saturable and reversible. It is maximal between pH 5.5 and 8.5 at an ionic strength of mu = 0.10 and decreases as a function of increasing salt concn, with half saturation near physiologic ionic strength. Scatchard analysis of binding data indicates a single class of sites with an average association constant in the order of 1.5 x 10(9)/M and an average number of 2.5 x 10(6) binding sites per cell. Unlabeled globular fragments of Clq inhibit intact 125I-Clq binding by 64%, while unlabeled collagen-like fragments have no effect. Thus it appears that binding of Clq to this high-affinity site is mediated by a region of the globular domain of the molecule. Only the fibroblast subtype with binding sites for the globular domain of Clq appear to have the capacity to induce non-immune activation of the classical complement cascade, as assessed by the generation of C4a and C4d fragments in normal AB serum following exposure to the cells. This activation may generate products that account for a previously reported complement mitogenicity for fibroblasts.

Binding Sites↗

PubMed1998

Genetic and immunologic studies of patients on procainamide.

Forty (40) patients with cardiac arrhythmias receiving procainamide (PA) therapy and 24 patients who were receiving other drugs for their cardiac disorders were investigated for class II HLA phenotypes and their DRB1*04 and DQB1*03 subtypes. Other genetic marker evaluations in the PA patients included: 1) class III MHC C4A and C4B null alleles of complement; and, 2) acetylation phenotype. Twenty (20) of the PA patients were also tested for the ability of their stimulated cells to secrete Interleukin-1 (IL-1 beta) and tumor necrosis factor (TNF alpha). We also examined the spontaneous production of these cytokines by peripheral blood leukocytes (PBL) from patients who were receiving chronic PA treatment. The results revealed no association of acetylation phenotypes with the class II HLA phenotypes nor class III MHC C4 allotypes in these patients. The results did show a significant increase in class III C4 complement allotypes in the PA patients when compared to the controls. The results also showed a significant increase in autoantibodies and DQw3 phenotypes in the PA patient group when compared to control populations. Results of spontaneous IL-1 and TNF production suggested there may be an association of select class II HLA phenotypes in some patients and this may be relevant to host responsiveness to PA treatment.

Acetylation↗

PubMed2004

Possible protective role for C-reactive protein in atherogenesis: complement activation by modified lipoproteins halts before detrimental terminal sequence.

BACKGROUND: Previous work indicated that enzymatically remodeled LDL (E-LDL) might activate complement in atherosclerotic lesions via a C-reactive protein (CRP)-dependent and CRP-independent pathway. We sought to substantiate this contention and determine whether both pathways drive the sequence to completion. METHODS AND RESULTS: E-LDL was prepared by sequential treatment of LDL with a protease and cholesteryl esterase. Trypsin, proteinase K, cathepsin H, or plasmin was used with similar results. Functional tests were used to assess total complement hemolytic activity, and immunoassays were used to demonstrate C3 cleavage and to quantify C3a, C4a, C5a, and C5b-9. E-LDL preparations activated complement to completion, independent of CRP, when present above a threshold concentration (100 to 200 microg/mL in 5% serum). Below the threshold, all E-LDL preparations activated complement in dependence of CRP, but the pathway then halted before the terminal sequence. Native LDL and oxidized LDL did not activate complement under any circumstances tested. Immunohistological analyses corroborated the concept that CRP-dependent complement activation inefficiently generates C5b-9. CONCLUSIONS: Binding of CRP to E-LDL is the first trigger for complement activation in the atherosclerotic lesion, but the terminal sequence is thereby spared. This putatively protective function of CRP is overrun at higher E-LDL concentrations, so that potentially harmful C5b-9 complexes are generated.

Arteriosclerosis↗

PubMed2004

Cloning, expression, cellular distribution, and role in chemotaxis of a C5a receptor in rainbow trout: the first identification of a C5a receptor in a nonmammalian species.

C3a, C4a, and C5a anaphylatoxins generated during complement activation play a key role in inflammation. C5a is the most potent of the three anaphylatoxins in eliciting biological responses. The effects of C5a are mediated by its binding to C5a receptor (C5aR, CD88). To date, C5aR has only been identified and cloned in mammalian species, and its evolutionary history remains ill-defined. To gain insights into the evolution, conserved structural domains, and functions of C5aR, we have cloned and characterized a C5aR in rainbow trout, a teleost fish. The isolated cDNA encoded a 350-aa protein that showed the highest sequence similarity to C5aR from other species. Genomic analysis revealed the presence of one continuous exon encoding the entire open reading frame. Northern blot analysis showed significant expression of the trout C5a receptor (TC5aR) message in PBLs and kidney. Flow cytometric analysis showed that two Abs generated against two different areas of the extracellular N-terminal region of TC5aR positively stained the same leukocyte populations from PBLs. B lymphocytes and granulocytes comprised the majority of cells recognized by the anti-TC5aR. More importantly, these Abs inhibited chemotaxis of PBLs toward a chemoattractant fraction purified from complement-activated trout serum. Our data suggest that the split between C5aR and C3aR from a common ancestral molecule occurred before the emergence of teleost fish. Moreover, we demonstrate that the overall structure of C5aR as well as its role in chemotaxis have remained conserved for >300 million years.

Amino Acid Sequence↗

PubMed1990

Effect of exercise on complement activity.

Complement measurements of C1, C1q, C2, C3, C4, C5; the anaphylatoxins, C3a, C4a, and C5a; and total hemolytic activity of the classical and alternative pathways were made in 26 experienced adult runners before and after shortterm aerobic exercise. The baseline results were compared with those of nonexercising age-matched controls. In most subjects tested, running resulted in nanogram increases in C3a and C4a with corresponding decreases in the hemolytic activity of C4 (C4H). Baseline values of C3 and C4H were decreased significantly in runners when compared with nonexercising controls. Preliminary studies measuring the effect of exercise on C3a levels were also done in three asthmatic runners. Mean resting and postexercise levels, and exercise-induced increases in C3a anaphylatoxin in the asthmatic subjects were significantly higher than in the nonasthmatic subjects. The findings indicate that short-term exercise results in the activation of C3 and C4 and subsequent generation of C3a and C4a anaphylatoxins, and suggest that both activation of the classical pathway of complement and a selective downregulation of C3 production may occur in persons regularly engaged in aerobic exercise. The exaggerated generation of C3a by asthmatic subjects during exercise raises the possibility that anaphylatoxins play an etiologic role in exercise-induced asthma.

Adult↗

PubMed1990

Counterregulatory effects of interferon-gamma and endotoxin on expression of the human C4 genes.

Susceptibility to autoimmune disease is associated with null alleles at one of the two genetic loci encoding complement protein C4. These two genetic loci, C4A and C4B, are highly homologous in primary structure but encode proteins with different functional activities. Expression of C4A and C4B genes is regulated by IFN-gamma in human hepatoma cells and in murine fibroblasts transformed with the respective genes. In these cell lines, IFN-gamma has a significantly greater and longer-lasting effect on expression of C4A than that of C4B. In this study we examined synthesis and regulation of C4A and C4B in peripheral blood monocytes from normal, C4A-null, and C4B-null individuals. Synthesis of C4 in human peripheral blood monocytes decreases during time in culture. IFN-gamma mediates a concentration- and time-dependent increase in steady-state levels of C4 mRNA and a corresponding increase in synthesis of C4 in normal human monocytes. LPS decreases monocyte C4 expression and completely abrogates the effect of IFN-gamma on the expression of this gene. In contrast, LPS and IFN-gamma have a synergistic effect in upregulating expression of another class III MHC gene product, complement protein factor B. The effect of LPS on constitutive and IFN-gamma-regulated C4 synthesis is probably not mediated via release of endogenous monokines IL-1 beta, TNF-alpha, or IL-6. Synthesis of C4, and regulation of its synthesis by IFN-gamma and LPS, are similar in normal, C4A-, and C4B-null individuals. These results demonstrate the synthesis of C4 at extrahepatic sites and tissue-specific regulation of C4 gene expression.

Complement C4↗

PubMed1990

The effect of antibody isotype on the activation of C3 and C4 by immune complexes formed in the presence of serum: correlation with the prevention of immune precipitation.

Radioimmunoassays for C3a and C4a have been used to measure the activation of complement during the formation of immune complexes in human serum by the interaction of DNP-BSA and each of 11 mouse anti-DNP monoclonal antibodies of varied isotype and affinity. Those containing IgG2 or IgM were potent activators of C4, whilst IgG1 containing complexes were less efficient. C3 activation in normal serum was similar for complexes containing IgG1, IgG2a, IgG2b or IgM. IgA complexes did not activate C3 or C4. All complexes except those containing IgA precipitated more slowly in serum than in buffer. IgG2 antibodies were potent activators despite being very slow to precipitate in buffer. In serum containing EGTA activation of C4 was abolished and precipitation of complexes occurred at the same rate as in buffer. Nevertheless, C3 activation still occurred by the alternative pathway for all IgG and IgM complexes. Antibodies of the same isotype did not necessarily activate complement to the same extent. The ranking of the ability to activate complement was the same as that observed when performed complexes containing the same antibodies were added to serum. The levels of C4a generated were similar under both conditions but for most antibodies more C3a was generated by preformed complexes.

Antibodies, Monoclonal↗

PubMed1976

A cyanogen bromide fragment of beta-galactosidase from Escherichia coli with alpha-donor activity in complementation of the enzyme from mutant M15.

Aminoethylated beta-galactosidase from Escherichia coli was cleaved by CNBr. The fragment C4a was purified by gel filtration and ion-exchange chromatography. The molecular weight of the fragment C4a was determined to be 9000 +/- 600. The N-terminal amino acid was found to be isoleucine. Qualitative examination of homogeneity was carried out by disc-gel electrophoresis. The fragment C4a was shown to be active as an alpha donor in complementation of beta-galactosidase activity in vitro with E. coli mutant M15, which has a deletion in the alpha region of the z gene. The molecular weights of complementable fractions from mutant M15 were found to be 123 000 +/- 2500 and 507 000 +/- 11 000, and of the complemented enzyme 522 500 +/- 11 400.

Amino Acids↗

PubMed1995

Population and family studies of three disease-related polymorphic genes in systemic lupus erythematosus.

The contribution to systemic lupus erythematosus (SLE) of three lupus-associated polymorphisms (involving the C4A2 complement component, Humhv3005 and the T cell antigen receptor alpha chain gene) are investigated in 81 individuals from 14 multiplex SLE families, 41 unrelated lupus patients, and 88 unrelated healthy controls. The results show a strong association between C4A deletion and SLE in these families. While the current study confirms the previously reported association between hv3005 deletion and sporadic SLE, the study fails to support this association in familial SLE patients. Moreover, no correlation is detected between the occurrence of hv3005 deletion and C4A null alleles in lupus patients, suggesting that the effects of these genetic polymorphisms on predisposition to lupus are independent. The previously reported lupus-associated T cell receptor (TCR) alpha chain polymorphism is not detected in any of the individuals studied here. The combined data suggest that C4A null alleles predispose strongly to development of lupus, whereas the influence of hv3005 deletion is relatively weak. The results also suggest that contributions of weak susceptibility genes such as hv3005 to disease predisposition may be obscured by the effects of stronger genetic factors and thus need to be examined in patients lacking these factors.

Base Sequence↗

PubMed1985

C4B3 allotype with a novel Ch phenotype.

The fourth component of complement (C4) has two classes of protein, C4A and C4B, both of which have many allelic forms. The serological determinants Rodgers (Rg1, Rg2) and Chido (Ch1, Ch2, Ch3) are generally associated with C4A and C4B, respectively. The C4B3 allotype has been detected in a single Canadian family that expresses a novel Ch phenotype, Ch:-1, 2, -3. There was no information for the Rg determinants, as the C4A*2B*3 haplotype would normally express Rg on the C4A protein. Other C4B3 allotypes in informative families have different Ch phenotypes, and the relationships of these within extended major histocompatibility complex haplotypes are discussed in this paper.

Alleles↗

PubMed1999

Possible mechanism for in vitro complement activation in blood and plasma samples: futhan/EDTA controls in vitro complement activation.

BACKGROUND: Ongoing in vitro complement (C) activation in citrate or EDTA plasma has prevented an accurate analysis of C-activation products generated in vivo. The aim of this study was to characterize handling and storage conditions required to prevent in vitro C activation in blood and plasma samples collected with Futhan/EDTA. METHODS: Biotrak(TM) RIAs were used to quantitatively measure C3a and C4a in blood and/or plasma samples from healthy individuals (controls) and from liver transplant patients. Blood samples were routinely drawn into either EDTA (1 g/L) tubes or into tubes containing both EDTA (1 g/L) and Futhan (0.1 g/L) and immediately centrifuged at 2000g for 15 min at 4 degrees C. RESULTS: In controls, C4a, but not C3a, in fresh samples (time 0) was higher in EDTA plasma than in Futhan/EDTA plasma (n = 20; P = 0.002). Futhan/EDTA prevented C3a and C4a generation in blood and plasma samples held at room temperature (22-23 degrees C) for 1 h and in plasma held for 24 h at 4 degrees C or -70 degrees C. The mean C3a concentration (1.76 mg/L; n = 19) at time 0 in EDTA plasma samples from liver transplant patients was significantly higher than for controls (0.34 mg/L; n = 11). In these patients, the mean C3a in EDTA samples increased to 13.8 mg/L after 60 min at room temperature, but there was no change in the C3a concentration of an EDTA plasma from a control. In the patients, C3a concentrations were lower in Futhan/EDTA plasma than in EDTA at time 0 and after 60 min at room temperature (1.40 and 2.02 mg/L, respectively). The mean patient C4a was 4.02 mg/L in EDTA plasma at time 0 vs 0.24 mg/L for controls; it increased to 16.9 mg/L after 60 min at room temperature compared with 0.76 mg/L for controls. The mean patient C4a was 0.83 mg/L in Futhan/EDTA plasma at time 0 vs 0.1 mg/L for controls. Neither patient nor control C4a concentrations increased vs time in Futhan/EDTA. CONCLUSION: The combination of Futhan (0.1 g/L) and EDTA (1 g/L) eliminates in vitro C activation.

Adult↗

PubMedDate not supplied

The possibility of improving biocompatibility by removing anaphylatoxins from the circuit of blood-perfused artificial organs.

The possibility of reducing bioreactivity during extracorporeal circulation by removing bioactive substances "turned on" in the devices is described in this paper. The bioreaction and bioactive products, as represented by neutrophil reaction and activated complement fragments generated during the use of a blood-perfused artificial organ, were studied as a model. Hemoperfusion with activated charcoal (AC) was used to remove the activated complement fragments. The adsorption of anaphylatoxins (C3a, C4a, and C5a) was evaluated following plasma perfusion through AC in vitro, all three of which were satisfactorily adsorbed. Six kinds of AC (three HEMA coated AC, two uncoated AC, and one cellulose coated AC) were compared with respect to adsorption of C5a in vitro. Uncoated AC adsorbed well and rapidly, but the coating with HEMA made adsorption take place slowly. The cellulose coating activated complement and did not decrease plasma C5a levels. After the adsorption of anaphylatoxins was confirmed, each of the AC columns was placed on-line after a cuprophan dialyzer in five chronic hemodialysis patients. C3a levels and neutrophil counts were compared with those obtained during usual hemodialysis (HD). By using heparin treated, uncoated AC, elevation of C3a levels and transient neutropenia were suppressed. Peak C3a with AC was reduced by 150% compared with prevalues, and the neutropenia nadir increased from 20% to 40% of baseline. The adsorption ability influenced the reduction in neutropenia. The heparinized uncoated AC and the column with large volumes of HEMA-coated AC had the best effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylatoxins↗

PubMed2006

Which complement assays and typings are necessary for the diagnosis of complement deficiency in patients with lupus erythematosus? A study of 25 patients.

INTRODUCTION: Deficiencies in components of the classical pathway of complement activation are strong risk factors for lupus erythematosus (LE).Yet, it has not been addressed whether the conventional measurements of the serum hemolytic CH50 activity and antigenic concentrations of C3 and C4 are sufficient to asses a deficiency in C4A, C4B or C2 components, the most common deficiencies associated with LE. PATIENTS AND METHODS: In a retrospective series, we performed complement analyses in 35 patients with LE who were systematically screened for a complement deficiency. The majority of patients had cutaneous LE with mild systemic involvement and no complement consumption. Of 25 patients (72%) with complement deficiency we found 13 with a partial C4A deficiency, 2 with a complete C4A deficiency, 6 with a partial C4B deficiency, 2 with a complete C4B deficiency and 2 with a combined partial C2 and C4A deficiency. RESULTS: The total complement activity (CH50) was decreased in only one out of two patients with complete C4B deficiency. CH50 level was found to be low-normal (35-38 U/ml(-1)) in one patient with partial C4B deficiency, one patient with complete C4B deficiency and both patients with combined partial C4A and C2 deficiency. Total C4 levels were normal in 9 out of 13 the patients with a partial C4A deficiency and in 2 out of 6 patients with a complete C4B deficiency. The antigenic concentration of C3 was low in only 1 patients with a complete C4B deficiency and within the normal range in all the others patients. Overall, 50% of the patients had normal or elevated C3, C4, and CH50 levels. DISCUSSION: This study emphasizes that the usual measurements of CH50, C3 and C4 levels are not adequate to detect a C4 and/or C2 deficiency in patients with LE. In epidemiologic or investigative studies addressing the prevalence of complement deficiency, more elaborated diagnostic tests, such as C4 protein allotyping, C2 level measurement and genetic screening for type I C2 deficiency should also be performed.

Adult↗

PubMed1986

Oxygen free radical generation during cardiopulmonary bypass: correlation with complement activation.

To determine the relationships among complement activation, pulmonary leukosequestration, and oxygen free radical generation, we prospectively studied 15 patients undergoing cardiopulmonary bypass for myocardial revascularization. Plasma levels of C3a, C4a, and hydrogen peroxide (a marker of oxygen free radical generation) were measured before, during, and after extracorporeal circulation. The results confirm that cardiopulmonary bypass activates complement via the alternate (C3a) pathway. This first phase of complement activation was accompanied by an increase in plasma H2O2 (from 80 +/- 8 to 155 +/- 13 microM/ml; p less than .001) and by pulmonary sequestration of polymorphonuclear leukocytes. Protamine administration after cardiopulmonary bypass further activated complement via the classical (C4a) pathway but was not accompanied by a change in plasma hydrogen peroxide. We hypothesize that both complement activation and excess oxygen free radical generation contribute to the pathophysiology of extracorporeal circulation.

Blood Cells↗

PubMed1985

Complement activation in type 1 human diabetes.

Complement activation was quantitated in serum and plasma of diabetic and normal subjects by sensitive competitive equilibrium radioimmunoassays (RIA) for C3a, C4a, C5a, Factor B, and a newly described C5 neoantigen (termed C5 activation antigen, and abbreviated C5-AA) in a stable 54-kDa fragment of C5. Plasma C3a levels were significantly elevated in 8 of 16 patients with newly diagnosed Type 1 diabetes (P less than 0.0005) with the mean C3a concentration for these patients being more than 10-times greater than the mean value of normal controls. C4a levels were also elevated in 2 of these patients (P less than 0.02), but C5a levels, although higher than normal, were not significantly increased. In contrast, the levels of C5-AA in the serum of all patients (11/11) with chronic Type 1 diabetes were significantly higher than in control Type 2 patients (noninsulin-dependent diabetes) (P less than 0.0005) and 4 of 7 patients with new onset insulin-dependent diabetes mellitus also had significantly higher levels of C5-AA than the Type 2 patients (P less than 0.01). The levels of Factor B in the serum of 5 of 9 patients with new onset diabetes were significantly higher than normal (P less than 0.0025). Five recent onset Type 1 diabetes patients were evaluated longitudinally for C3a, C4a, and C5a: in 3 the levels of C3a were elevated during new onset disease decreasing into the normal range during remission; in 2 of these patients C4a was also significantly elevated and the levels decreased during remission; and in 3 patients the levels of C5a were not significantly elevated but they decreased during remission. Purified human complement proteins and complement hemolytic assays were used to measure complement activation in serum during incubation with rat pancreatic islet cells. With diluted normal human serum, less than 20% of C3 or Factor B were consumed during 30 min at 37 degrees C, while with new onset Type 1 diabetic patient sera up to 90% of C3 and Factor B were consumed in 5/6 sera and 4/6 sera, respectively. These findings suggest (a) that complement activation fragments C3a, C4a, and C5a are generated in vivo in new onset Type 1 diabetes; (b) that both the classical and the alternative complement pathways may be activated; and (c) that this may result in a measurable activation of C5 generating biologically and immunologically active C5a and other C5 activation fragments.(ABSTRACT TRUNCATED AT 400 WORDS)

Complement Activation↗

PubMed1989

Modulation of immunity in patients with autoimmune disease and cancer treated by extracorporeal immunoadsorption with PROSORBA columns.

Extensive animal studies and clinical observations support an immunosuppressive role for certain antibodies and circulating immune complexes (CIC) in malignant and autoimmune diseases. Investigators have attempted to correct or modulate dysfunction by removal of antibodies or CIC from plasma. Extra-corporeal immunoadsorption of plasma over columns containing a silica matrix and covalently attached highly purified staphylococcal protein A (PROSORBA column) is a procedure that specifically removes those plasma components by the interaction of protein A with the Fc region of IgG. The interaction of CIC with the Fc receptor on protein A has three specific results. First, there is direct removal of immunosuppressive CIC from the circulation. Studies of CIC-mediated immunosuppression in experimental systems have shown dose-response relationships over wide ranges of CIC concentrations. Thus, removal of CIC relative to the IgG antibody may be expected to exert some stimulation of the immune system. Second, the complement system is activated. Elevated levels of C3a, C4a, and C5a are observed in patients' circulating plasma after PROSORBA treatment. These levels peak one to three hours post-perfusion and are near normal levels by six hours post-perfusion. These complement components are stimulators of growth and activity of immune cells. In addition, by binding to CIC they stimulate clearance of CIC by the reticuloendothelial system. Thus, treatments may induce removal of more CIC than could be anticipated by the binding capacity of treatment columns. Third, antibody is released from CIC. Interaction of CIC with bound protein A with or without the aid of activated complement components leads to liberation of free antibody. Depending upon other factors, eg, amount of circulating antigen and/or unbound IgG, either free antibody or CIC containing more antibody relative to antigen (or both) may be infused into patients with the posttreatment plasma. Such CIC function as immune stimulators rather than suppressors of immune cell activity. The consequences of the treatments are summarized as follows. Stimulation of immune cellular activity is seen one to three hours posttreatment. During the first one to three treatments, cells of the granulocyte/macrophage series show the greatest increase. During and after treatments 2 to 4, lymphocytes show the greatest increase. At this point, increased blastogenic response to mitogens is observed along with an increase in the T helper/suppressor cell ratio.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗

PubMed1992

The value of complement measurements in the assessment of lupus activity.

The complement system was studied prospectively in 29 patients, predominantly renal (25), with systemic lupus erythematosus (SLE) to examine the value of complement assays in the distinction between active and inactive disease. Disease activity was evaluated primarily by clinical, biochemical and histological parameters which were obtained at the time of assessment. Fourteen patients had active disease, as assessed by clinical and laboratory criteria. C1q, C4, C4a, C2, C3, C3a, C5, total haemolytic activity (CH50) and complement inhibitors were measured in each patient. The ratios of C4a:C4 and C3a:C3 were also calculated. Values for all components except C5 were different between control subjects and active patients while only CH50 was different between inactive patients and controls. All parameters except C4a:C4 and C5 were different between active and inactive patients. There was a highly significant difference in the number of active patients with reduced levels of C2, C3 and C3a:C3 compared to inactive patients (i.e. p less than 0.001) whereas lesser or no difference was observed for other parameters. The concentration of complement inhibitors was elevated in both groups. We conclude that, among readily available complement parameters, C2 and C3 provide the best assessment of disease activity in patients with SLE.

Adult↗

PubMed1984

HLA-linked complement markers in Alzheimer's and Parkinson's disease: C4 variant (C4B2) a possible marker for senile dementia of the Alzheimer type.

We determined the gene frequencies for the alleles of the HLA-linked complement markers C2, properdin factor B (BF), C4A (Rodgers) and C4B (Chido), and the red cell enzyme glyoxalase-I in 38 unrelated patients with senile dementia of the Alzheimer type, 42 patients with idiopathic Parkinson's disease, and 59 unaffected, aged-matched control blood donors. In senile dementia of the Alzheimer type and in Parkinson's disease, no significant difference was found in the gene frequencies of alleles at either the BF, C2, or GLO-I locus compared with those of age-matched controls. In senile dementia of the Alzheimer type, a striking increase in the frequency of the rare C4B locus allele, C4*B2, was apparent, resulting in the high relative risk of RR = 8.8 (p less than 0.0001) for this disorder.

Alleles↗