Anti-alpha-fodrin antibodies in patients with Sjögren's syndrome secondary to rheumatoid arthritis

Nisihara, Renato; Skare, Thelma L.; Cenci, Elisa; Gabardo, Denise; Nass, Flavia; Utiyama, Shirley R. R.

doi:10.5935/1676-2444.20160023

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LABORATORY MEDICINE, Original Article • J. Bras. Patol. Med. Lab. 52 (3) • May-Jun 2016 • https://doi.org/10.5935/1676-2444.20160023 copy

Anti-alpha-fodrin antibodies in patients with Sjögren's syndrome secondary to rheumatoid arthritis

Anticorpos antialfafodrina em pacientes com síndrome de Sjögren secundária a artrite reumatoide

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Introduction:

The Sjögren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration. The currently most researched antibodies for its diagnosis are anti-La and anti-Ro, which, however, have low specificity in the case of SS secondary to rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). The antibodies against alpha-fodrin (AF) have been proposed to diagnose SS.

Objective:

In the present study, we investigated the anti-AF antibody in a group of RA patients with and without secondary SS (sSS).

Methods:

Were studied 90 consecutive patients with RA (48.8% of them with SS), and samples of 45 healthy volunteers. Anti-AF immunoglobulin class G (IgG) and anti-AF immunoglobulin class A (IgA) were investigated by enzyme-linked immunosorbent assay (ELISA) and were considered positive when >15 U/ml. Demographic, clinical, and serological data were obtained from chart reviews.

Results:

Anti-AF IgA was positive in 46/90 (51.1%) of the RA sample and 3/45 (6.7%) of controls (p < 0.001); anti-AF IgG was found in 21/90 (23.3%) of RA patients and none of controls (p = 0.037). Neither IgA nor IgG anti-AF antibodies showed significant difference in patients with and without sSS.

Conclusion:

In our study, anti-AF IgA and anti-AF IgG neither alloweded diagnosis of sSS in RA patients, nor marked any special clinical or serological finding.

Key words:
Sjögren's syndrome; autoimmunity; autoantibodies; arthritis rheumatoid

Antibody	RA without sSS	RA with sSS	p (Mann-Whitney)
Anti-AF IgA	6-35	8-40	0.97
(U/ml)	Median 15 (11.5-20.5)	Median 14 (12-19)
Anti-AF IgG	5-38	7-48	0.68
(U/ml)	Median 12 (8-15)	Median 11 (9-14)

Variables	Anti-AF IgA			Anti-AF IgG
Variables	Positive n = 46	Negative n = 44	p	Positive n = 21	Negative n = 69	p
Gender (male/female)	9/37 (24.3%)	4/40	0.13^# # Fisher's exact test;	4/17	9/69	0.27^# # Fisher's exact test;
Mean age at diagnosis (years)	40 ± 12.2	41.3 ± 13.23	0.64^* * Student's t-test;	37.6 ± 10.95	41.5 ± 13.06	0.22^* * Student's t-test;
Median disease duration (months)	90 (IQR 48-168)	84 (IQR 36-132)	0.48^ Mann-Whitney test;	72 (IQR 48-132)	84 (IQR 24-210)	0.89^ Mann-Whitney test;
Ethnic background (Caucasians/Afro-descendants)	37/9	33/11	0.53^ϯ ϯ chi-square test.	15/6	55/14	0.42^ϯ ϯ chi-square test.
Rheumatoid nodules	5/46 (2.1%)	3/44 (6.8%)	0.71^# # Fisher's exact test;	2/21 (9.5%)	6/69 (8.7%)	1^# # Fisher's exact test;
Lung fibrosis§	7/41 (17%)	0/42	0.005^# # Fisher's exact test;	3/17 (17.6%)	4/66 (6%)	0.14^# # Fisher's exact test;
Secondary Sjögren's	20/43 (46.5%)	21/41 (51.2%)	0.66^ϯ ϯ chi-square test.	8/18 (44.4%)	33/66 (50%)	0.67^ϯ ϯ chi-square test.
Hypothyroidism	5/46 (10.8%)	6/40 (15%)	0.74^# # Fisher's exact test;	2/20 (10%)	9/68 (13.2%)	1^# # Fisher's exact test;
Rheumatoid factor	36/45 (80%)	28/43 (65.1%)	0.11^ϯ ϯ chi-square test.	17/20 (85%)	47/68 (69.1%)	0.25^# # Fisher's exact test;
Anti-CCP	32/38 (84.2%)	25/35 (71.4%)	0.18^ϯ ϯ chi-square test.	14/16 (87.5%)	43/57 (75.4%)	0.49^# # Fisher's exact test;
Antinuclear antibody	9/44 (20.4%)	2/42 (4.7%)	0.04^# # Fisher's exact test;	3/20 (15%)	8/66 (12.1%)	0.71^# # Fisher's exact test;
Anti-Ro	4/44 (9.1%)	3/42 (7.1%)	1^# # Fisher's exact test;	1/20 (5%)	6/66 (9.1%)	1^# # Fisher's exact test;
Tobbaco exposure	16/42 (38.1%)	14/39 (35.8%)	0.83^# # Fisher's exact test;	6/19 (31.5%)	24/63 (38.1%)	0.60^ϯ ϯ chi-square test.
Steinbrocker functional index
Class 1	4/45 (8.8%)	0/42	0.04^ϯ ϯ chi-square test.	11/20 (55%)	26/67 (38.8%)	0.13^ϯ ϯ chi-square test.
Class 2	6/45 (13.3%)	6/42 (14.3%)	-	8/20 (40%)	26/67 (38.8%)	-
Class 3	21/45 (46.6%)	13/42 (30.9%)	-	0	12/67 (17.9%)	-
Class 4	14/45 (31.1%)	23/42 (54.8%)	-	1/20 (5%)	3/67 (4.5%)	-

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[1] CORRESPONDING AUTHOR: Renato Nisihara. Rua João Azolin, 660; Santa Felicidade; CEP: 82015-040; Curitiba-PR, Brasil; Phone/fax: +55 (41) 9911-9572; e-mail: renatonisihara@up.edu.br.