Association of Serum Complement C3 Levels with Severity and Mortality in COVID 19

Sojit Tomo; Pvsn Kiran Kumar; Dharamveer Yadav; Shrimanjunath Sankanagoudar; Jayakaran Charan; Abhishek Purohit; Vijaya Lakshmi Nag; Pradeep Kumar Bhatia; Kuldeep Singh; Naveen Dutt; Mahendra Kumar Garg; Sanjeev Misra; Praveen Sharma; Purvi Purohit

doi:10.1007/s12291-023-01148-x

Association of Serum Complement C3 Levels with Severity and Mortality in COVID 19

Indian J Clin Biochem. 2023 Oct;38(4):447-456. doi: 10.1007/s12291-023-01148-x. Epub 2023 Aug 16.

Affiliations

¹ Department of Biochemistry, All India Institute of Medical Sciences (AIIMS) Jodhpur, Basni Phase 2, Jodhpur, Rajasthan 342005 India.
² Department of Biochemistry, Andhra Medical College, Visakhapatnam, India.
³ Department of Pharmacology, All India Institute of Medical Sciences, Jodhpur, India.
⁴ Department of Pathology and Lab Medicine, All India Institute of Medical Sciences, Jodhpur, India.
⁵ Department of Microbiology, All India Institute of Medical Sciences, Jodhpur, India.
⁶ Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Jodhpur, India.
⁷ Department of Paediatrics, All India Institute of Medical Sciences, Jodhpur, India.
⁸ Department of Pulmonary Medicine, All India Institute of Medical Sciences, Jodhpur, India.
⁹ Department of General Medicine, All India Institute of Medical Sciences, Jodhpur, India.
¹⁰ Department of Surgical Oncology, All India Institute of Medical Sciences, Jodhpur, India.

PMID: 37746543
PMCID: PMC10516839 (available on 2024-10-01)
DOI: 10.1007/s12291-023-01148-x

Abstract

The severe acute respiratory distress syndrome-associated coronavirus-2 infection can activate innate and adaptive immune responses which may lead to harmful tissue damage, both locally and systemically. C3, a member of complement system of serum proteins, is a major component of innate immune and inflammatory responses. This study is aimed to assess serum C3 as a marker of COVID-19 severity and a predictor of disease progression. A total of 150 COVID-19 patients, confirmed by RT-PCR, and 50 healthy controls were recruited. Serum C3 levels were determined by using direct colorimetric method. Median levels of serum C3 in total cases and controls were 157.8 and 165.7 mg/dL respectively. Serum C3 although not significantly decreased, they were lower in cases when compared to controls. Similarly, significant differences were found between the groups, with severe group (140.6 mg/dL) having low levels of serum C3 protein when compared to mild (161.0 mg/dL) and moderate group (167.1 mg/dL). Interestingly, during hospitalization, significant difference between baseline (admission) and follow-up (discharge) was observed only in patients with moderate disease. Based on our results, lower levels of C3, with an increase in IL-6 and d-dimer levels, are associated with higher odds of mortality. Therefore, we would like to emphasize that measuring serum C3 levels along with other inflammatory markers might give an added advantage in early identification of patients who are prone to having a severe disease course and can help in a more effective follow-up of disease progression.

Supplementary information: The online version contains supplementary material available at 10.1007/s12291-023-01148-x.

Keywords: C3; COVID-19; Complement system; IL-6.

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