Purification and characterization of a liver cell membrane specific antigen.

Antibodies against human liver cell membranes were raised in rabbits by immunizing 105,000 g precipitate of normal human liver homogenates (insoluble fraction). After absorption with non-liver antigens such as human spleen, kidney, lung homogenates and serum, the anti-liver cell membrane specific antigen (LCM) IgG fraction was prepared. The antibody reacted with both 105,000 g supernatant of the liver homogenate (soluble fraction) and Triton X-100 extract of the insoluble fraction, and with the surface of Chang liver cells. Using affinity columns to conjugate this antibody and other antibodies against non-liver antigens, LCM was prepared from the soluble fraction composed of 70K, 59K, 49K, and 31K proteins. These proteins of LCM were included in liver specific lipoprotein (LSP). The number of LCM proteins was limited to 4, although that of LSP was 8 or more. Furthermore, circulating antibodies against "LCM" were detected in patients with chronic liver diseases type B and autoimmune hepatitis by an 125I-LCM-IgG-Protein A method. Therefore, LCM may be more useful than LSP to study the immunological responses involved in liver diseases.