Mannose-binding lectin-low genotypes are associated with milder systemic and immunological disease expression in primary Sjögren's syndrome.
OBJECTIVE
To investigate the association of mannose-binding lectin (MBL)-low genotypes with the clinical and immunological expression of primary SS.


METHODS
Eighty-one patients with primary SS who fulfilled the 2002 classification criteria were included in the study. MBL2 polymorphisms were investigated by sequence-based DNA typing of the promoter and exon 1. Genotypes 0/0, 0/XA or XA/XA were considered as MBL-low and XA/A, A/0 and A/A as MBL-sufficient. Control groups included 46 patients who exclusively fulfilled the 1993 SS criteria, 114 SLE patients and 104 healthy individuals.


RESULTS
Twelve (15%) SS patients had MBL-low genotypes, of whom six (7%) had genotype 0/XA, five (6%) had genotype 0/0 and one (1%) had genotype XA/XA. A higher prevalence of the XA/A genotype (32 vs 17%, P = 0.01) was found in primary SS patients in comparison with SLE patients. No patient with primary SS carrying MBL-low genotypes had purpura, glomerulonephritis or neurological involvement (0 vs 29%, P = 0.025). Immunologically, patients carrying MBL-low genotypes had a lower frequency of anti-Ro/SS-A antibodies (17 vs 55%, P = 0.014), anti-La/SS-B antibodies (8 vs 48%, P = 0.009) and low C4/C3 levels (0 vs 32%, P = 0.016). No patient with primary SS carrying the homozygous MBL-deficient genotype 0/0 had anti-Ro/SS-A or anti-La/SS-B antibodies, low C3/C4 levels or circulating cryoglobulins.


CONCLUSIONS
SS patients with MBL-low genotypes have a less pronounced systemic and immunological disease expression in comparison with those carrying MBL-sufficient genotypes. In primary SS, MBL deficiency may represent a protective factor against the development of more aggressive autoimmune damage.
Ramos-Casals
M
M
Department of Autoimmune Diseases, Laboratory of Autoimmune Diseases Josep Font, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain. mramos@clinic.ub.es
Brito-Zerón
P
P
Soria
N
N
Nardi
N
N
Vargas
A
A
Muñoz
S
S
Bové
A
A
Suárez
B
B
Lozano
F
F
D001323:Autoantibodies / Q000097:blood; D001324:Autoantigens / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007113:Immunity, Innate; D008297:Male; D037601:Mannose-Binding Lectin / Q000235:genetics*; D050606:Mannose-Binding Protein-Associated Serine Proteases / Q000235:genetics; D008875:Middle Aged; D011110:Polymorphism, Genetic; D020733:RNA, Small Cytoplasmic / Q000276:immunology; D012189:Retrospective Studies; D012261:Ribonucleoproteins / Q000276:immunology; D012859:Sjogren's Syndrome / Q000235:genetics* / Q000276:immunology; D000099207:SS-A Antigen
D001323:Autoantibodies; D001324:Autoantigens; D015415:Biomarkers; D037601:Mannose-Binding Lectin; D050606:Mannose-Binding Protein-Associated Serine Proteases; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; C445619:MBL2 protein, human; C116006:RO60 protein, human; D000099207:SS-A Antigen; C105296:MASP2 protein, human