Circulating Immune Complexes and Complement Activation in Sensitized Kidney Transplant Recipients

• Published in: International journal of molecular sciences Vol. 25; no. 20; p. 10904
• Main Authors: Trivyza, Maria Stella, Stergiopoulou, Charikleia, Tsakas, Sotiris, Ntrinias, Theodoros, Papasotiriou, Marios, Karydis, Nikolaos, Papachristou, Evangelos, Goumenos, Dimitrios S.
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 10.10.2024; MDPI
• Subjects: Adult; Aged; Antibodies; Antigen-Antibody Complex - blood; Antigen-Antibody Complex - immunology; Antigens; Cardiovascular disease; Complement Activation - immunology; Complement C1q - immunology; Complement system; Cross-Sectional Studies; Female; Graft Rejection - blood; Graft Rejection - immunology; Health aspects; Hemodialysis; Humans; Immune complexes; Isoantibodies - blood; Isoantibodies - immunology; Kidney diseases; Kidney Transplantation - adverse effects; Kidney transplants; Kidneys; Lymphocytes; Male; Middle Aged; Neutrophils; Organ transplant recipients; Patients; Physiological aspects; Transplant Recipients; Transplantation; Greece; donor-specific antibodies; immune complexes; kidney transplantation; CH50
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms252010904

Chronic antibody-mediated rejection in kidney transplantation is a common cause of graft loss in the late post-transplant period. In this process, the role of the classical complement activation pathway is crucial due to the formation of immune complexes between donor-specific antibodies (DSAs) and donor antigens and the attachment of the C1q complement fragment. This study aimed to determine the levels of circulating C1q immunocomplexes (CIC-C1q) and complement activation (CH50), in sensitized kidney transplant recipients (KTRs). In this cross-sectional study we used serum samples from KTRs with de novo or preformed DSAs (n = 14), KTRs without DSAs (n = 28), and 22 subjects with no history of chronic kidney disease (controls). C1q immunocomplexes and CH50 concentration in serum were measured with the enzyme immunoassay (EIA) kit MicroVue CIC-C1q (Quidel, Athens, OH, USA) and EIA kit MicroVue CH50 (Quidel, OH, USA), respectively. Higher concentrations of CIC-C1q was observed in KTRs with DSAs in comparison with controls and with KTRs with no DSAs (6.8 ± 2.7 and 4.8 ± 1.9 vs. 5.0 ± 1.2 μg Eq/mL, respectively, p < 0.01). We found no difference in CIC-C1q between KTRs with no DSAs and controls. CIC-C1q levels were positively correlated with DSA titer. CH50 levels were decreased in KTRs with DSAs in comparison with controls and KTRs with no DSAs (39 ± 15 vs. 68 ± 40 and 71 ± 34 U Eq/mL, respectively, p < 0.01). There was no difference in CH50 between DSA-negative KTRs and controls. Kidney transplant recipients with DSAs had increased serum levels of C1q immunocomplexes and increased classical pathway complement activation.