Autoantibodies in Acquired Hemolytic Anemia With Special Reference to the LW System

Most autoantibodies in patients with warm antibody autoimmune hemolytic anemia (AIHA) have specificity within the Rh system. Using rare cells such as -D- and Rh_null cells, Weiner and Vos (1963) described specificity against normal cells (nl), partially deleted cells (pdl), and deleted cells (dl). Recently, autoantibodies which failed to react with Rh_null cells that were of anti-U specificity have been described. It was suggested that the "Rh related" autoantibodies that cannot be identified as specific Rh antibodies may be anti-U. In the present study we examined eluates from the red cells of eight patients with AIHA using a panel of extremely rare cells and cross-absorption and elution techniques. We demonstrated autoantibody specificities not definable without the rare cells and, further, defined heterogeneity of the LW antigen. Autoantibodies with U specificity occurred in three eluates only. It was always present with an antibody of another specificity. Six of the eluates contained anti-LW, two anti-nl, five anti-pdl, three anti-dl, and one anti-e. Absorption and elution studies using the rare Rh-positive LW-negative (Mrs. Bigelow) showed that anti-pdl may in fact represent anti-LW + LW₁ and that Mrs. Bigelow may represent a weak variant of LW. Injection of her red cells into guinea pigs produced an anti-LW that reacted similarly to the antibody produced by injecting Rh-positive LW-positive cells. An analogy to the ABO is suggested that normal Rh-positive LW-positive cells represent LW₁, Rh-negative LW-positive cells represent LW₂, Mrs. Bigelow represents LW₃ and Rh_null cells represent the only true LW-negative (lw).