Increased dimeric IgA producing B cells in the bone marrow in IgA nephropathy determined by in situ hybridisation for J chain mRNA.
OBJECTIVE
To investigate the possible role of the systemic IgA immune system in the pathogenesis of IgA nephropathy


METHODS
J chain mRNA expression in the IgA cells of the bone marrow was studied. Bone marrow trephine biopsy specimens from seven patients with IgA nephropathy and seven matched controls were examined by (1) non-isotopic in situ hybridisation (ISH) and (2) combined immunofluorescence and non-isotopic ISH to identify the plasma cell type. Serum polymeric IgA was also determined using standard high pressure liquid chromatography and sandwich enzyme linked immunosorbent assay.


RESULTS
Non-isotopic ISH revealed a similar number of J chain mRNA positive cells/unit length in biopsy specimens from patients (16.5 +/- 2.7 cells/mm) and controls (17.7 +/- 2.4 cells/mm). Combined immunofluorescence and ISH revealed a greater proportion of J chain mRNA positive IgA cells in patients (7.6 +/- 1.45%) compared with controls (3 +/- 0.8%). Serum polymeric IgA was similar in both patients (91 +/- 22 mg/l) and controls (77 +/- 24 mg/l).


CONCLUSIONS
These data suggest that excess production of dimeric IgA occurs in the bone marrow in IgA nephropathy.
Harper
S J
SJ
Department of Nephrology, Leicester General Hospital.
Allen
A C
AC
Pringle
J H
JH
Feehally
J
J
D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology*; D016022:Case-Control Studies; D005260:Female; D005455:Fluorescent Antibody Technique; D005922:Glomerulonephritis, IGA / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis* / Q000097:blood; D007144:Immunoglobulin J-Chains / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics
D007070:Immunoglobulin A; D007144:Immunoglobulin J-Chains; D012333:RNA, Messenger