This study aims to investigate the relevance of the Tfh/Tfr (Follicular helper T cells/ Follicular regulatory T cells) ratio in patients with IgA nephropathy:
* To identify a differential expression of the Tfh/Tfr ratio in patients considered stable or progressive * To predict, at diagnosis, the clinical evolution of the disease (progressive or stable form) in the first year.
IgA nephropathy histologically proven on renal biopsy according to KDIGO criteria, with 8 permeable glomeruli (patients diagnosed from 2009 with a minimum follow-up for their nephropathy of 5 years (arm 1) or patients diagnosed during the study (arm 2))
Legal incapacity or limited legal capacity
Subjects with no social security coverage.
Pregnancy / No effective contraceptive method