Detection Of C4d Deposition Research Articles

Clinical and immunological relevance of antibodies in solid organ transplantation.

The two important issues affecting recipients of solid organ transplants and of importance to immunologists are (i) sensitization of the recipient to HLA antigens and the resultant humoral immune response leading to the development of anti-HLA antibodies; and ii) development of robust assays for early detection of humoral rejection post-transplant. Evidence from several studies clearly indicates that presence of circulating anti-HLA antibodies especially donor specific leads to early graft loss and high titres of DSA may even lead to hyperacute or accelerated acute rejection. Long-term graft survival too is adversely affected by the presence of either pre- or post-transplant DSA. HLA matching status of the recipient - donor pair - is an important factor in the modulation of humoral response following transplantation and in a way affects de novo development of DSA. Data collected over the past decade clearly indicate significantly lower level of DSAs in optimally matched donor-recipient pairs. HLA mismatches especially those on HLA-DR and HLA-C loci have wider implications on post-transplant graft survival. The presence of circulating anti-HLA antibodies leads to endothelial damage in the newly grafted organ through complement dependent or independent pathways. Although detection of C4d deposition in renal biopsies serves as an important indicator of humoral rejection, its absence does not preclude the presence of DSAs and humoral rejection, and hence, it cannot be relied upon in every case. The emergence of epitope-based screening for anti-HLA antibodies on Luminex platform with high degree of sensitivity has revolutionized the screening for anti-HLA antibodies and DSAs. Studies indicate that humoral response to non-HLA antigens might also have a detrimental effect on allograft survival. High titres of such circulating antibodies may even lead to hyperacute rejection. Pre-emptive testing of solid organ recipients, especially kidney transplant recipients for anti-HLA and non-HLA antibodies and aggressive post-transplant monitoring of allograft function to detect DSAs using Luminex-based tests, is highly recommended.

Detection of C4d deposition in cardiac allografts: a comparative study of immunofluorescence and immunoperoxidase methods.

Abstract Context.—Complement activation, evidenced by deposition of C4d, is important in the diagnosis of antibody-mediated rejection of cardiac allografts. C4d deposition can be assessed by either immunofluorescence (IF)– or immunoperoxidase (IP)–based methods. The use of methods varies considerably among institutions, but there are few data addressing their diagnostic equivalence. Objective.—To compare IF and IP C4d staining on paired endomyocardial biopsy samples from a large number of heart transplant patients. Design.—Retrospectively selected paired frozen and paraffin-embedded samples from the same biopsy were stained for C4d by IF and IP methods. Capillary staining was scored by using a 0, 1+, 2+, 3+ scale. Results.—A total of 296 biopsy pairs from 70 patients were studied. There were two hundred forty-three cases that were scored 0, twenty-four scored 1+, sixteen scored 2+, and thirteen scored 3+ by IF. Two hundred thirty-one cases scored 0, forty scored 1+, ten scored 2+, and fifteen scored 3+ by...

Detection of C4d Deposition in Cardiac Allografts: A Comparative Study of Immunofluorescence and Immunoperoxidase Methods

Complement activation, evidenced by deposition of C4d, is important in the diagnosis of antibody-mediated rejection of cardiac allografts. C4d deposition can be assessed by either immunofluorescence (IF)- or immunoperoxidase (IP)-based methods. The use of methods varies considerably among institutions, but there are few data addressing their diagnostic equivalence. To compare IF and IP C4d staining on paired endomyocardial biopsy samples from a large number of heart transplant patients. Retrospectively selected paired frozen and paraffin-embedded samples from the same biopsy were stained for C4d by IF and IP methods. Capillary staining was scored by using a 0, 1+, 2+, 3+ scale. A total of 296 biopsy pairs from 70 patients were studied. There were two hundred forty-three cases that were scored 0, twenty-four scored 1+, sixteen scored 2+, and thirteen scored 3+ by IF. Two hundred thirty-one cases scored 0, forty scored 1+, ten scored 2+, and fifteen scored 3+ by IP. Complete agreement was seen in 81% of cases. Among discrepant cases, 89% (n = 51) were minor (±1) and 11% (n = 6) were major (±2). Five of the 6 major discrepancy biopsies came from 2 patients, both of whom had concordant (IF and IP) 3+ results on prior biopsies. The weighted κ value for the entire sample set was 0.78 and for the first biopsy only set (to correct for bias introduced by multiple biopsies from the same patient) the weighted κ value was 0.88. Immunofluorescence and IP C4d staining methods are highly comparable and are both viable options for antibody-mediated rejection surveillance in transplant heart biopsies.

92: Detection of C4d Deposition in Cardiac Allografts: A Comparative Study of Immunofluorescence and Immunoperoxidase Methods

Complement activation, evidenced by deposition of C4d, is important in the diagnosis of antibody-mediated rejection of cardiac allografts. C4d deposition can be assessed by either immunofluorescence (IF) or immunoperoxidase (IP) based methods. The use of methods varies considerably among institutions, but there are few data addressing their diagnostic equivalence. The purpose of this study was to compare IF and IP C4d staining on paired endomyocardial biopsy samples from a large number of heart transplant patients.

Antibodies, isotypes and complement in allograft rejection

Classical complement activation is a key step in the process of antibody-mediated rejection. Emphasizing novel diagnostic strategies, this study will discuss recent studies highlighting the particular relevance of alloantibodies with complement-fixing ability. Reinforcing the pivotal role of complement, numerous studies have shown tight associations of capillary C4d deposition, a 'footprint' of alloantibody-triggered complement activation, with the occurrence of allograft injury. Distribution patterns of immunoglobulin isotypes or subclasses, which strongly differ in their ability to activate complement, may not adequately reflect the actual pathogenetic relevance of detected allosensitization. This fact may be explained by the finding that other variables, such as antibody-binding density or a synergism of antibodies against different epitopes of the same antigen, may contribute to complement activation. An attractive approach to distinguish between complement-fixing and presumably less harmful noncomplement-fixing alloreactivities could be the detection of C4d deposition in vitro. Applying such techniques, recent studies have shown that human leukocyte antigen reactivity with C4d-fixing ability, in contrast to noncomplement-fixing sensitization, may strongly predict antibody-mediated rejection and inferior graft survival. Considering the pivotal role of complement, technologies that uncover the complement-fixing ability of alloantibodies may be of particular interest for the selective detection of deleterious sensitization.