Study of the C5a/C5aR1 Axis in IgG4-associated Disease: a Potential Therapeutic Target
This is a monocentric, comparative, cross-sectional, case-control study seeking to identify abnormalities of the C5a-C5aR1 axis between a population of patients with active IgG4-associated disease (MAG4) and two control groups: healthy subjects without MAG4 and patients with MAG4 in remission.
- EligibilityCriteria: Inclusion Criteria for patients suffering from IG4-related disease and patients in remission :  age > 18 diagnosis of IgG4-associated disease according to ACR/EULAR 2019 classification criteria (4,5) with a score ≥20. disease activity score (IgG4-RD Responder Index) ≥2 in at least one affected organ  Exclusion Criteria for patients suffering from IG4-related disease and patients in remission :  presence of a differential diagnosis ("IgG4-RD mimicker") or exclusion criterion according to ACR/EULAR 2019 classification criteria (4,5). systemic corticosteroid treatment ≥5 mg/day ongoing or < 1 month ; Study C5-MAG4_RCAPHM21_0433 Protocol Version 1.1 of 16/01/2024 Page 15 of 41 immunosuppressive therapy ongoing or < 3 months ; current biotherapy treatment or < 6 months; absence of signed informed consent; absence of affiliation to a Social Security scheme. patient participating in an ongoing therapeutic trial ; any condition which, in the opinion of the investigator, could influence the results of the study.  Inclusion criteria for healthy volunteers :  - age > 18  Exclusion criteria for healthy volunteers :  infectious episode (temperature >38°C, flu-like signs) in the 30 days prior to inclusion; known inflammatory (including IG4-related disease) or autoimmune pathology; treatment with corticosteroids in progress or taken in the month prior to sampling, or immunosuppressants in progress or taken in the 3 months prior to sampling, or biotherapy in the 6 months prior to sampling; absence of signed informed consent; absence of affiliation to a Social Security scheme; persons taking part in an ongoing therapeutic trial; any condition which, in the opinion of the investigator, could influence the results of the study. - HealthyVolunteers: Accepts Healthy Volunteers - Gender: All - MinimumAge: 18 Years - StdAgeList: Adult, Older Adult