IgA mesangial deposits in C3H/HeJ mice after oral immunization with ferritin or bovine serum albumin(1)
The IgA deposited in the kidney are polymeric and presumably of mucosal origin. C3H/HeJ mice were selected because they exhibit high IgA responses. Mice were immunized orally with ferritin: 10 mg in 0 2 ml by gastric intubation on the first and second days followed by 1 mg/ml of drinking water for 1 month.
The serum level of IgA was significantly higher in immunized than in non-immunized C3H/HeJ. After immunization the IgA level was significantly higher in C3H/HeJ than in C3H/eB.
From 17 C3H/eB and 20 C3H/HeJ mice immunized with ferritin, all except four C3H/HeJ mice had significant levels of anti-ferritin IgG in their serum, 10 C3H/eB and six C3H/HeJ had anti-ferritin IgM and four C3H/eB and four C3H/HeJ had anti-ferritin IgA.
IgA deposits were significantly more intense in immunized C3H/HeJ mice. The intensity of mesangial IgA deposits clearly correlated with the total IgA level in the serum. The presence of ferritin and the anti-ferritin specificity of immunoglobulins deposited in the kidney could not be demonstrated.
Haematuria was not detectable in any animal. Proteinuria was present traces to + in both groups of animals without significant difference.
Spleen would serve not only as an intermediate organ in the homing pattern of IgA precursor cells from GALT to distant mucosal tissues including the lamina propria of the gut but also as a target organ for systemic IgA responses. C3H/HeJ mice exhibit enhanced IgA responses due to a greater T cell helper activity induced in the GALT of these LPS non-responsive mice. The higher levels of IgA in the serum of C3H/HeJ mice compared to C3H/eB confirm the immunogenetic prevalence of the IgA response in that strain. Polymeric IgA is rapidly transported from the plasma to the bile in several species by a mechanism which probably involves secretory component acting as an hepatocyte membrane receptor.