6. 自己免疫性溶血性貧血をいかに治療するか

抄録

Autoimmune hemolytic anemia (AIHA) is a disease characterized by the presence of anti-red cell autoantibody on red cells and, in about a half of the patients, in their sera. Shortening of the red cell survival in vito is due mainly to the enhanced phagocytosis by macrophage through Fc-receptors.
Production of the autoantibody is resulted from organic or functional derangement of lymphocytes. Although the etiology of AIHA has not yet been clarified, the genetic and environmental factors are considered important in the derangement of the immune system.
Corticosteroids have been widely and effectively used for treatment of AIHA as the first choice drug. As is well known, the drugs are not curative ones. Clinical and experimental efforts are being made toward developement of newer treatment which leads to cure of AIHA.
1. It was shown that there was a marked decrease in suppressor function of T lymphocytes in a patient with AIHA. From the in vitro experiment, corticosteroids in certain concentrations showed the enhancing effect on concanavalin A (Con A) induced suppressor T lymphocyte. This was revealed in the assay system by measuring T lymphocyte proliferation in response to stimulation of non-T lymphocyte in mixed lymphocyte culture and B lymphocyte proliferation to poke weed mitogen. The suppressor enhancing effects are not long-lasting in vivo when corticosteroids are given patients with AIHA. A new treatment should be deviced to focus upon how to maintain longterm enhancement of suppressor T-lymphocyte.
2. NZB/W F₁ mice are model animals of human systemic lupus erythematosus. Abouta half of the mice develope the anti-red cell antoantibody and show positive Coombs'test. Fractionated electron beam irradiation of total 2,000 rad resulted in a marked prolongation of survival as compared with non-radiated controls. Few of the irradiated mice showed positive Coombs' test long after the irradiation. It was postulated that long-term maintenance of enhancement of suppressor T lymphocytes was obtained by the irradiation.
3. Mycoplasma pneumonia is sometimes associated with hemolytic anemia of cold autoantibody type. Elimination of the mycoplasma using antibiotics such as tetracyclin and erythromycin leads to a complete cure of the hemolytic anemia. α-Methyl dopa is an antihypertensive drug which is known to cause, in some patients, Coombs' positive hemolytic anemia after long-term administration. Discontinue of the drug in the patients with hemolytic anemia brings a gradual improvement of anemia and, several months later, Coombs' test becomes negative. In the idiopathic AIHA of warm autoantibody type, it is postulated but not yet convincingly established that the environmental factors would invade into body and play a role in the developement of the disease. If this is true, the elimination of the factors out of body could lead to a complete cure of AIHA.