Clinical value of autoantibodies against C1q in children with glomerulonephritis.
OBJECTIVE
Autoantibodies against C1q (anti-C1q) have been found in a number of autoimmune and renal diseases. They are best described in adult patients with systemic lupus erythematosus, where a strong correlation between the occurrence of anti-C1q and severe lupus nephritis (LN) has been observed. However, the role of anti-C1q in children with systemic lupus erythematosus has not yet been determined. Furthermore, the clinical importance of anti-C1q in other forms of glomerulonephritis remains to be elucidated. The aim of this study was to investigate anti-C1q in children with different forms of glomerulonephritis including LN.


METHODS
We prospectively investigated 112 children with different forms of newly diagnosed glomerulonephritis for the presence of anti-C1q by an enzyme-linked immunosorbent assay and compared them with healthy controls. Associations between anti-C1q and disease manifestations at the time of the measurements and during follow-up were investigated.


RESULTS
Twenty-one of 112 patients were positive for anti-C1q compared with 0 of 40 healthy controls. Anti-C1q was associated with activity in LN and with disease severity in patients with acute poststreptococcal glomerulonephritis (APSGN). In LN, 7 of 12 patients were found to be anti-C1q positive. Six of these 7 had active disease at the time of the serum sampling compared with 1 of 5 of the anti-C1q-negative children. In children with APSGN, 8 of 24 were positive for anti-C1q. Anti-C1q-positive APSGN patients had significantly higher proteinuria and more often hypertension than those without anti-C1q. All 4 patients in which APSGN did not resolve spontaneously were anti-C1q positive.


CONCLUSIONS
Anti-C1q is associated with active LN in children. In addition, children with anti-C1q-positive APSGN have more severe disease than those who are anti-C1q negative. These data suggest APSGN is another disease in which anti-C1q has a pathogenic role.
Kozyro
Ina
I
Department of Pediatrics, 2nd Children's Hospital, Belarus State University, Minsk, Belarus.
Perahud
Iryna
I
Sadallah
Salima
S
Sukalo
Alexander
A
Titov
Leonid
L
Schifferli
Jürg
J
Trendelenburg
Marten
M
D000293:Adolescent; D001171:Arthritis, Juvenile / Q000150:complications / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D015922:Complement C1q / Q000276:immunology*; D003176:Complement C3 / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005921:Glomerulonephritis / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D008181:Lupus Nephritis / Q000175:diagnosis / Q000276:immunology; D008297:Male; D013290:Streptococcal Infections / Q000150:complications / Q000276:immunology
D001323:Autoantibodies; D015415:Biomarkers; D003176:Complement C3; D015922:Complement C1q