Related Experiment Video

Updated: Oct 2, 2026

Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells
06:29

Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells

Published on: January 29, 2014

Complement phenotypes in glomerulonephritis: increased frequency of homozygous null C4 phenotypes in IgA nephropathy

R H McLean, R J Wyatt, B A Julian

    Kidney International
    |December 1, 1984
    PubMed

    Insights

    Individuals with a C4 homozygous null phenotype show increased frequency in IgA nephropathy and Henoch-Schönlein purpura (HSP) patients. This suggests a potential predisposition to these conditions associated with C4 gene variants.

    Area of Science:

    • Immunogenetics
    • Nephrology
    • Rheumatology

    Background:

    • The major histocompatibility complex (MHC) contains complement genes like C4A, C4B, and BF, known for their polymorphism.
    • Complement gene variants, particularly null alleles, are implicated in various autoimmune and inflammatory conditions.

    Purpose of the Study:

    • To investigate the association between complement gene polymorphism (C4A, C4B, BF) and the prevalence of IgA nephropathy and Henoch-Schönlein purpura (HSP).
    • To determine if specific C4 null allele patterns correlate with an increased risk for developing IgA nephropathy or HSP.

    Main Methods:

    • Studied polymorphism of C4A, C4B, and BF genes in 48 IgA nephropathy and 19 HSP patients using immunoelectrophoretic techniques.
    • Assessed functional C4 activity via sheep cell overlay in agarose with C4 deficient sera.
    • Categorized subjects into four groups based on the presence or absence of C4 null variants, including homozygous null phenotypes.

    Main Results:

    • Patients with IgA nephropathy or HSP exhibited a significantly higher frequency of the C4 homozygous null phenotype (17.8%) compared to controls (3.9%, P = 0.0031).
    • Both IgA nephropathy (P = 0.045) and HSP (P = 0.003) patient groups showed a greater prevalence of the C4 homozygous null phenotype.
    • Serum C4 concentration was elevated in patients (740 mg/ml) versus controls (576 µg/ml, P < 0.001).

    Conclusions:

    • A C4 homozygous null phenotype is associated with an increased frequency in patients with IgA nephropathy and HSP.
    • This finding suggests a potential genetic predisposition towards developing IgA nephropathy or HSP in individuals with the C4 homozygous null phenotype.
    • Further research is warranted to elucidate the exact significance of this association.

    More Related Videos

    Measuring Erythrocyte Complement Receptor 1 Using Flow Cytometry07:20

    Measuring Erythrocyte Complement Receptor 1 Using Flow Cytometry

    Published on: May 19, 2020

    Analyses of Proteinuria, Renal Infiltration of Leukocytes, and Renal Deposition of Proteins in Lupus-prone MRL/lpr Mice09:43

    Analyses of Proteinuria, Renal Infiltration of Leukocytes, and Renal Deposition of Proteins in Lupus-prone MRL/lpr Mice

    Published on: June 8, 2022

    Related Concept Videos

    Complementation Tests00:49

    Complementation Tests

    A complementation test is a simple cross to identify whether the two mutations are located on the same gene or different genes. It was first performed by Edward Lewis in the 1940s while working on fruit flies. He developed the test to identify the location and arrangement of different mutations on chromosomes.
    Organisms heterozygous for different mutations are crossed pairwise in all combinations. If present on different genes, the mutations can complement each other by providing the missing...
    Renal Corpuscle01:20

    Renal Corpuscle

    The glomerulus and Bowman's capsule are two essential components of the nephron, which is the functional unit of the kidney. These microscopic structures play a critical role in the process of blood filtration to produce urine.
    Glomerulus: Structure and Function
    The glomerulus is a tiny, intricate network of capillaries located at the beginning of the nephron. It's enveloped by the Bowman's capsule and receives its blood supply from an afferent arteriole, which divides into numerous capillaries...
    Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu01:29

    Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu

    Genetic variations significantly influence drug response through pharmacokinetics, receptor interactions, and biologic milieu modifications. Pharmacokinetic alterations impact drug metabolism and clearance, affecting efficacy and toxicity. Variants in drug-metabolizing enzymes, such as CYP2C9 and CYP2C19, alter drug activation and elimination. For example, CYP2C9 loss-of-function variants require lower warfarin doses to prevent excessive bleeding, while CYP2C19 variants reduce clopidogrel...
    Hypersensitivity Reactions: Cytolytic Reactions01:01

    Hypersensitivity Reactions: Cytolytic Reactions

    Type II hypersensitivity involves IgG and IgM antibodies targeting cell surface antigens, leading to cell destruction. This can occur through complement activation, antibody-dependent cell-mediated cytotoxicity (ADCC), or acting as opsonins for phagocytosis. When excessive, these reactions cause significant tissue damage.Drug-induced hemolytic anemia is a common example, where drugs like penicillin or cephalosporins bind to red blood cells, forming drug-protein complexes. These complexes...
    Nephrotic Syndrome I : Introduction01:24

    Nephrotic Syndrome I : Introduction

    Nephrotic Syndrome is a chronic kidney disorder defined by clinical findings such as severe proteinuria, hypoalbuminemia, hyperlipidemia, and edema. These symptoms result from damage to the glomeruli, the kidney’s filtering units, increasing their permeability to proteins.Definition and Meaning:Proteinuria, defined as the loss of more than 3.5 grams of protein per day in adults, is a crucial feature of nephrotic syndrome. This condition is often accompanied by edema, the accumulation of fluid...
    Hypersensitivity Reactions: Immune-Complex Reactions01:19

    Hypersensitivity Reactions: Immune-Complex Reactions

    Type III hypersensitivity reactions occur when antigen–antibody complexes form and activate the complement system. Normally, these complexes help the clearance of antigens by phagocytes and red blood cells. However, when large numbers of immune complexes are present, they can deposit in tissues—particularly in the walls of blood vessels—leading to inflammation and tissue injury. These deposits trigger complement activation and neutrophil recruitment, resulting in serum sickness, a systemic...