Presence of IgG in IgA nephropathy immunecomplexes
Immunecomplexes in IgA nephropathy are though to be composed by IgG autoantibodies directed to galactose-deficient IgA1 (Gd-IgA1) produced by mucosal lymphoid tissue.
Take home messages
Routine immunofluorescence is able to detect IgA in mesangial deposits, but fails to highlight IgG in more then 50% of cases
IgG extracted from tissue of patients affected by IgA nephropathy demonstrated specifity for IgA1 and not for other antigens (eg PLA2R)
This specificity has been demonstrated also for cases without IgG+ immunofluorescence
These IF-negative cases were analyzed by confocal microscopy, demonstrating co-localization of IgG and IgA