Effects of K-76 monocarboxylic acid, an anticomplementary agent, on various in vivo immunological reactions and on experimental glomerulonephritis.

K-76 monocarboxylic acid (K-76 COOH) caused rapid reduction in hemolytic activities of complement and some of its components, especially C5, when injected into guinea pigs or rats. K-76 COOH suppressed Forssman shock in guinea pigs and mice and heterologous passive cutaneous anaphylaxis in guinea pigs. It also reduced the amount of protein excreted in the urine of rats with nephrotoxic nephritis and greatly prolonged the survival of (NZB X NZW) F1 female mice with a spontaneous systemic lupus erythematosus-like disease. The glomeruli of mice treated with K-76 COOH retained almost the normal histological appearance even at 1 year of age. K-76 COOH-treated mice became less sensitive to the infection of Escherichia coli, staphylococcus aureus, or Streptococcus pneumoniae, probably by enhancement of phagocytosis due to inhibition of factor I. K-76 COOH did not have any significant effect on a delayed-type contact skin reaction in mice, or on experimental allergic encephalitis in guinea pigs.