Anti Ssb In Serum

Introduction

Highly purified SSB antigen is bound to microwells & stabilized for extended shelf life. Diluted patient sera are placed in the microwells & incubated. If anti- SSB antibodies are present, they will bind to the antigen in the microwell. The microwells are then washed to remove residual sample & a second incubation with anti-human IgG conjugated to alkaline phosphatase is carried out. The conjugate will bind immunologically to the anti- SSB IgG antigen- antibody complex, forming a 'sandwich' consisting of:
Conjugate (Enzyme-labeled Anti-human IgG)
Human anti- SSB ( IgG)
Well Coated with SSB antigen
Unbound conjugate is removed in the subsequent washing step. Enzyme substrate is then added to the microwell & if bound conjugate is present, the colorless substrate (p-nitrophenyl phosphate), will be hydrolyzed to form a yellow end product, ( p-nitrophenol). The reaction is then stopped and the color fixed. The intensity of the color is measured photometrically at 405 nm & is proportional to the concentration of anti- SSB present in the patient sample.

SSB antibodies,(identical to the previously described La antibody), are found in approximately 15% of patients with systemic lupus erythematosus ( SLE). They are primarily considered a serological marker for Sjogren's Syndrome- sicca complex & are detected in approximately 60% of such patients. As with anti-SSA ( Ro) antibody, anti- SSB (La) is frequently detected in precipitin assays in sera yielding false-negative ANA by immunofluorescence techniques.
Anti- SSB invariably occurs in sera containing anti- SSA antibodies and virtually all anti- SSB-positive sera contains anti-SSA. There appear to be important differences that distinguish SLE patients who produce only anti-SSA from those producing both anti-SSA & SSB. There is a great similarity in nonrenal findings in these two groups, but there is a striking difference in the frequency and severity of renal disease. SLE patients producing both SSA and SSB antibodies have a much lower incidence of nephritis than those patients producing anti-SSA alone. Since the presence of anti- SSB antibodies, therefore, is associated more frequently with a milder form of autoimmune disease their detection would aid in the diagnosis & therapy of rheumatic disease.
Neonatal lupus effects 1-2% of children with mothers having anti-SSA or anti- SSB, regardless if mother has SLE or Sjogren's syndrome.

Serum is separated from the clot & refrigerated, 2-8 degrees C for short term storage or stored frozen, -20 degrees C, for long term storage. Avoid freeze-thaw cycles. CAUTION: Serum samples should not be heat inactivated, as this may cause false positive results.

Henry, John Bernard, Clinical Diagnosis amd Management by Laboratory Methods, W. B. Saunders Co., Philadelphia, 1991. pp 891-892.
The Physicians Guide to Anti-DNA Antibody Testing, Diamedix Corporation, Miami, Aug. 1989. pp 1-6.
Summary of Procedure. DiaMedix Corporation, Miami, June 1991. pp 1-8.

anti-SSB/La in serum