Aplastic Anæmia: Evidence for an Immunological Mechanism

Suppressor cell-mediated neutropenia in Felty's syndrome.

“…Subpopulations of T cells, called regulator or suppressor cells, have been shown to inhibit various immune parameters (10). Hyperactive suppressor cells have been implicated in the pathogenesis of the decreased immunoglobulin (Ig) synthesis in some patients with common variable hypogammiinzaglobulinemia (11), the decreased levels of n1on1-paraprotein Ig in mnultiple myeloma (12), the failure of hematopoiesis in some patients with idiopathic aplastic anemia (13), the decreased erythropoiesis in Diamond-Blackfan Syndrome (14), and in the anergyaccompanying systemic fungal infections (15). On the other hand, defective suppressor cell function has been shown by us to be present and possibly responsible for the emergence of autoreactive clones in active systemic lupus erythematosus (16).…”

Effects of Chloramphenicol Reduction Products on Hemopoietic Precursor Cells in vitro

“…Also, cells from aplastic patients have been demonstrated to suppress granulopoietic CFC (1) and erythro poietic CFC (6) from normal patients. Ascensao et al (1) also demonstrated that pretreatment of bone marrow cells from aplastic patients with anti-thymocyte globulin plus complement enhanced the number of granulopoietic CFC in in vitro agar cultures. These findings suggest that in vivo immunoregulatory effects of chlor amphenicol-reduction products merit further investigation.…”

“…There is very little evidence supporting the first three postu lates in either drug-induced or congenital aplas tic anemia; however, there is increasing evi dence that suppressor T cells play a role in at least some cases of aplastic anemia. Suppres sor T cells are becoming increasingly implicated in the pathogenesis of disease states in man, including diabetes mellitus (5), common vari able hypogammaglobulinemia (11), and recent ly in aplastic anemia (1,6). It is interesting that some patients have recovered from aplastic anemia after immunosuppressive therapy with out bone marrow transplants or after rejection of the bone marrow transplant (7).…”

Treatment strategies for patients with severe aplastic anemia

“…4 These results have led to the hypothesis that acquired AA is an immune-mediated disease of the bone marrow. 5,6 The degree of progenitor cell depletion is of the order of 99%, as shown with long-term culture-initiating cells and is seen for decades after successful treatment with immunosuppressive therapy (IST). 7 Treatment of acquired SAA includes BMT and IST.…”