Enzyme Immunoassay for the Detection of auto antibodies to SS-A in Human Serum.

Systemic rheumatic diseases are characterized by the presence of antinuclear antibodies (ANA) against nuclear macromolecules. Specific combinations of circulating ANA are the distinctive features of the different types of autoimmune diseases. Therefore, identification of specific auto antibodies is important in the diagnosis and treatment of the autoimmune diseases.

Antibodies to SS-A (Ro) have been detected in 60 - 70% of patients with Sjorgren's Syndrome and 25 - 30% of systemic lupus erythematosus (SLE). 60% of ANA-negative SLE patients and 63% of individuals diagnosed with subcutaneous erythematosus possess circulating anti-SSA antibodies. In addition, the presence of anti-SSA antibodies has been strongly correlated with complement C2 and C4 deficiencies, neonatal congenital heart block, and neonatal lupus. In recent years, immuno-diffusion has been the predominant method of choice for the detection of anti-SS-A antibodies; however, this technique has proven to be time-consuming and relatively insensitive.

SUMMARY OF 510 (k) SS-A

MDI SS-A Test reagents (P/N: SAKi-G) are intended for the semi-quantitative determination of IgG antibodies to SS-A in human serum. The principal diagnostic value of this test is detection of autoantibodies, which are used as an aid in patients with rheumatoid diseases. The Micro Detect, Inc. SS-A reagent (MDI SS-A Test) is intended to be used as a manual procedure. The reagents are supplied as a micro plate coated with specific antigens and Controls, Wash Buffer, Sample Diluent, Conjugate, Substrate, and Stop Solution. The patient results obtained using the MDI SS-A Test is substantially equivalent to those obtained by using predicate assays:

Relative Sensitivity: 100%

Relative Specificity: 97.2 %

Precision: 3.23-6.42(Inter) and 1.73-5.52(Intra)

Stability: One year at 2-8 C. The stability of the MDI SS-A Test Kit for the detection of IgG antibodies to SS-A was found to be one year at 2-8 C. This was predicted from studies done under stress condition (37 C). Real time stability is being monitored at 2-8 C.The MDI SS-A Test system is shown to be safe and effective and provide results, which are substantially equivalent to those, obtained by predicate products