[IgG subclasses of warm red cell autoantibodies in autoimmune hemolytic anemia].

IgG subclasses (G-sub) of warm red cell autoantibodies (anti-Rs) were examined by means of antiglobulin test (DAT) using anti-IgG1, 2, 3, and IgG4 sera (Holland Red Cross) on 12 AIHA, and on 5 cases being DAT positive caused by alpha-methyldopa (alpha MD). In 4 of 5 AIHA cases complicating SLE, the anti-Rs comprised not only IgG, but also IgA, IgM and C3; their G-sub were IgG1 + 2 in 2 and IgG1 + 2 + 3 + 4 in the other 2. In all of the 3 cases with idiopathic AIHA, anti-Rs comprised IgG alone (IgG1 alone, IgG1 + 3 or IgG1 + 2 + 3 in each one). All of the 5 alpha MD induced anti-Rs comprised IgG1 alone. Observation of the course of AIHA revealed that, although IgG3 tended to correlate with their anemia, this trend was not universal. Besides, the G-sub were not related to the anti-Rs titers. Furthermore, the immunological aberrations in patients with AIHA + SLE were found to be more complicated.