Elevated levels of antibodies to polyuridylic acid detected and quantitated in systemic scleroderma patients by solid phase radioimmunoassay.

A solid support radioimmunoassay has been developed to detect immunoglobulin specific circulating antibodies to polyuridylic acid (Pol U), single-stranded RNA (ss RNA), and single-stranded DNA (ss DNA) in scleroderma and other connective tissue diseases. The assay system uses flex-vinyl microtiter plates on which bovine methyl albumin, the respective polynucleotide, a 1:80 dilution of patient serum, and tritiated high affinity anti-IgG, -IgA, or -IgM are layered. The individual wells containing the sandwich assay are then counted for the presence of labeled immunoglobulins and the results are reported in microgram/ml.