CHARACTERISATION OF ANTI-LIVER KIDNEY MICROSOMAL |[lpar]|LKM|[rpar]| ANTIBODY IN CHILDRE WITH AUTOIMMUNE CHRONIC ACTIVE HEPATITIS |[lpar]|aCAH|[rpar]|

摘要

LKM antibody defines a subgroup of aCAH in childhood, characterised by a severe prognosis. To define the nature of this antibody we have determined, by indirect immunofluorescence technique, isotype and complement fixing ability of this antibody in 10 patients. Using anti-total immunoglobulin (Ig), anti LKM titres ranged between 1:40 and 1:160. When tested for the immunoglobulin classes IgG, IgM and IgA, LKM antibody proved to be IgG in all cases. When IgG subclasses were investigated, 9 of 10 patients had IgG1 titres similar to those obtained with anti-total Ig (1:80-1:640). IgG2 LKM antibody was present in low titre in 3 patients (1:20, 1:20, 1:40), including the one negative for IgG1. IgG4 LKM antibody was positive in two cases (1:40, 1:160), while no patient had IgG3 LKM antibody. In all instances anti-LKM proved to be abli, to fix complement (1:40-1:640). The restriction to the IgG1 isotype of anti-LKM antibody suggests a strong genetic influence on its production. Since LKM antibody has been shown to cross-react with liver plasma membrane (1) it is conceivable that this autoantibody contributes to liver damage by activating complement(1) Lenzi M, et al., Clin.Exp.Immunol.1984, 55, 36-40