Studies on Soluble Antigenic Substances Isolated from Human Liver

Summary Non-particulate cellular cytoplasmic constituents from human liver were isolated by physicochemical procedures. These substances were reactive as antigens in complement fixation tests against sera from patients with lupus erythematosus and other diseases. Results indicated that the soluble fraction constituents were not extracted from the cell nuclei. Fractionation of the soluble fraction by isoelectric precipitation at low ionic strength produced 3 active precipitates each of which reacted differently in complement fixation tests with sera from patients with lupus erythematosus. Enzymatic studies suggested that the substance active as antigens were RNA-protein and protein.