Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Comparison of Serum Free Light Chains, Interferon and Interleukins as Biomarkers of Disease Activity in Systemic Lupus Erythematosus (SLE).

Francis4,  Serene, Aggarwal6,  Rohit, Mikolaitis4,  Rachel, Niewold5,  Timothy B., Chubinskaya4,  Susanna, Block1,  Joel A., Sequeira2,  Winston

Rush University Medical Center, Chicago, IL
Rush University Medical Center, Chicago, IL
Rush University Medical Center, Section of Rheumatology, Chicago, IL
Rush University Medical Center, Section of Rheumatology
University of Chicago, Section of Rheumatology, Chicago, IL
University of Pittsburgh Medical Center

Background:

SLE may affect any organ and is associated with significant morbidity and mortality. Other than DsDNA in the context of Lupus nephritis, studies thus far exploring a biomarker for disease flare have been equivocal. We previously reported superior utility of serum free light Chains (FLC) compared to DsDNA and IgG as biomarkers for disease activity in SLE. We also reported that Total FLC (TFLC) elevation was greater in SLE as compared to rheumatoid arthritis, and that its association with diseaseactivity was stronger in SLE than rheumatoid arthritis. There have been studies by other authors showing association of Interleukin-6 (IL-6), Interleukin-10 (IL-10) and Interferona (IFN-a) with SLE disease activity. Herein, we compare the utility of total FLC with IL-6, IL-10 and IFN- a for disease activity in SLE.

Aims:

To determine the association of (1)serum TFLC with IL-6, IL-10 and IFN-a (2)to compare their association of disease activity, demographic variables (age. gender and ethnicity), immunosuppressive agents and ACR criteria.

Methods:

This is a cross-sectional study of 134 SLE patients (ACR criteria) recruited from a University Center from 2008–2010. PGA and SLEDAI were assessed by the same physician. Adjusted SLEDAI was calculated by deleting DsDNA and complement items from the SLEDAI. Serum was tested for TFLC (The Binding Site U.K), IL-6, IL-10 and IFN-a. Chart review was done for demographics, clinical and serological characteristics and treatment. Statistical analysis performed included correlation analysis, Mann Whitney test.

Results:

Mean age of the patients was 43±12 yrs; females composed 91% of the study group; African American 50%, Caucasians 24%,Hispanic 16%. PGA (Mean±SD, Median) was 0.5±0.6, 0, while SLEDAI was 4±4, 2. Forty eight percent patients were on prednisone. The (mean±SD, median) values were: TLC (58±64, 43), IL-6 (6±7, 4), IL-10 (16±20, 13) and IFN-a (21±39, 4). TFLC was correlated with IFN-a (r=0.37, p=0.0001) and IL-6 (r=0.25, p=0.009). IFN-a correlated with IL-6 (r=0.20, p=0.05).

TFLC showed a moderate correlation with PGA (r=0.39, p=0.002), SLEDAI (r=0.35, p=0.001) and adjusted SLEDAI (r=0.34, p=0.005). IL-10 was moderately associated with adjusted SLEDAI (r=0.32, p=0.02). IL-6 weakly correlated with SLEDAI (r=0.23, p=0.04) but not with adjusted SLEDAI. IFN-a was not associated with either of them.

IFN-a correlated with age (r=0.22, p=0.02), while IL-6 correlated with height (r=0.22, p=0.04). TFLC, IFN- a and IL-6 showed correlation with ethnicity. TFLC correlated with use of prednisone (r=0.30, p=0.001) while IFN-a correlated with use of methotrexate (r=0.20, p=0.04).

Conclusion:

Serum TFLC is moderately correlated with PGA and adjusted SLEDAI. Strength of TFLC association with adjusted SLEDAI is greater than observed with IL-10. Longitudinal studies to determine if changes in disease activity result in changes in TFLC are now indicated.

To cite this abstract, please use the following information:
Francis, Serene, Aggarwal, Rohit, Mikolaitis, Rachel, Niewold, Timothy B., Chubinskaya, Susanna, Block, Joel A., et al; Comparison of Serum Free Light Chains, Interferon and Interleukins as Biomarkers of Disease Activity in Systemic Lupus Erythematosus (SLE). [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1147
DOI: 10.1002/art.28913

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