title: An immunoglobulin G inhibiting lactate dehydrogenase activity.
abstract: We found extremely low (6 U/l) serum lactate dehydrogenase (LDH, EC 1.1.1.27) activity in a patient with uterine myoma. The patient's serum inhibited purified LDH isoenzymes. One milliliter serum neutralized 73 U purified LDH-1 isoenzyme, equivalent to 300-500-fold the amount of LDH in 1 ml of normal serum. The serum inhibitor was purified by ordinary procedures using chromatographies and identified as IgG which contains both kappa- and lambda-chains. The IgG is very unique in showing higher affinity to the H- than M-subunit of the LDH tetramer, in contrast with the IgGs already reported. After removal of the myoma, the anti-LDH activity gradually decreased with a half-life of 20 days corresponding to that of IgG and finally almost disappeared. This indicates a possibility that the myoma cells produce some factors such as B-cell growth and differentiation factors.
mesh_terms: D002845:Chromatography / Q000379:methods; D004586:Electrophoresis / Q000379:methods; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000502:physiology*; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000276:immunology*; D007889:Leiomyoma / Q000201:enzymology* / Q000276:immunology; D008875:Middle Aged; D014594:Uterine Neoplasms / Q000201:enzymology* / Q000276:immunology
chemical_list: D007074:Immunoglobulin G; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase