Background: Latent mesangial immunoglobulin (Ig)A deposition in long-term functioning kidney does not correlate with disease progression and may exhibit fluctuating patterns Mesangial IgA deposition without urinary abnormalities (latent mesangial IgA deposition) is occasionally observed in non-episode biopsies of kidney allografts. However, the histologic features of latent IgA deposition have not been fully characterized.
Methods: To better identify the clinicopathologic background of subclinical mesangial IgA deposition, we compared the clinical and histologic characteristics of long-term functioning kidney allografts with and without latent IgA deposition.
Results: Among 29 patients with a posttransplant duration of >10 years, 37.9% exhibited latent mesangial IgA deposition. Biopsies indicated that renal function at the time of and 5 years before subclinical mesangial IgA deposition was generally similar. HLA-DR4 and HLA-Bw51 showed a nonsignificant trend to be more frequent in the IgA-positive group. Histologic investigation demonstrated no changes in disease scores based on the Banff 2009 classification between groups. Immunofluorescence revealed co-deposition of C3 at >1+ intensity in 72% IgA-positive patients. Immunohistochemical analysis revealed that IgA deposition per se did not cause notable increases in intraglomerular α-smooth muscle actin (SMA)-positive cells. One patient with subclinical IgA deposition demonstrated a waxing and waning pattern in the amount of IgA deposition.
Conclusion: This study suggests that subclinical IgA deposition in long-term functioning kidney allografts is not associated with progressive course in clinical and pathologic findings. Furthermore, the amount of subclinical IgA deposition may exhibit fluctuating patterns in some cases.
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