Bactericidal/permeability-increasing protein and cathepsin G are the major antigenic targets of antineutrophil cytoplasmic autoantibodies in systemic sclerosis.
OBJECTIVE
To study the prevalence and antigenic specificity of antineutrophil cytoplasmic autoantibodies (ANCA) in patients with systemic sclerosis (SSc).


METHODS
Sera from 68 patients with SSc were screened for ANCA by indirect immunofluorescence (IIF) assay and for antibodies to myeloperoxidase (MPO) by ELISA. All sera positive for ANCA on IIF were analyzed for reactivity against antigenic targets other than MPO [bactericidal/permeability-increasing protein (BPI), cathepsin G, lysozyme, elastase, PR3, and lactoferrin]. Twenty-three sera negative for ANCA were also tested for antibodies to BPI and cathepsin G using ELISA.


RESULTS
The study included 33 patients with diffuse and 35 with limited SSc. ANCA was detected in 24 of the 68 sera (35.3%). In these 24 sera the antigenic targets were BPI in 14, cathepsin G in 13, and MPO in 8. Sera of 11 patients had reactivity against both BPI and cathepsin G. In sera, that were negative for ANCA, antibodies to BPI (4/23), cathepsin G (3/23), and MPO (1/44) were found in a small proportion of patients. Patients with antibodies to BPI had lower skin score, whereas no patient with antibodies to MPO had renal disease.


CONCLUSIONS
BPI and cathepsin G are the major antigenic targets of ANCA seen in patients with SSc. Patients with antibodies to BPI had lower skin scores.
Khanna
Dhanita
D
Department of Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
Aggarwal
Amita
A
Bhakuni
Darshan S
DS
Dayal
Rajeshwar
R
Misra
Ramnath
R
D000293:Adolescent; D000328:Adult; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins / Q000276:immunology*; D056649:Cathepsin G; D002403:Cathepsins / Q000276:immunology*; D000939:Epitopes; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D009195:Peroxidase / Q000276:immunology; D012595:Scleroderma, Systemic / Q000453:epidemiology / Q000276:immunology*; D012697:Serine Endopeptidases; D016036:Seroepidemiologic Studies
D019268:Antibodies, Antineutrophil Cytoplasmic; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D000939:Epitopes; D008565:Membrane Proteins; C021623:bactericidal permeability increasing protein; D009195:Peroxidase; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G