A microELISA assay to detect anti-liver-specific protein antibodies in the sera of patients with liver diseases.

A microELISA to detect anti-liver-specific protein (LSP) antibodies in human sera is described. Rabbit LSP was used as antigen. Optimal conditions for antigen concentration, serum dilution, substrate incubation time and reproducibility with time were established. The microELISA is specific, as assessed by testing anti-LSP positive sera with another lipoprotein from rabbit plasma (VLDL), although a weak cross-reactivity between LSP and VLDL was observed. The test was applied to patients with HBsAg-positive and -negative chronic active hepatitis (CAH). Ten of 26 (38%) patients were positive for anti-LSP antibodies, in comparison with healthy controls used to determine the threshold of positivity. Such a percentage is comparable with that reported for radioimmunoassay (RIA) procedures.