Studies on levamisole--induced agranulocytosis.

Widespread clinical trials of leavo-tetramisole (levamisole) as an immunopotentiating agent in rheumatoid arthritis, metastatic carcinoma, and immunodeficiency states have been complicated by agranulocytosis (AGC) in 2.5%-13% of patients. Other than a relationship with prolonged high dosage, very little is known regarding the pathogenesis of levamisole-induced AGC. Whereas leukoagglutination was negative, fluorochromatic microgranulocytotoxicity (GCY) tests were positive with serum from 10 of 10 acutely neutropenic patients. The antibody was IgM, reacted with 100% of unrelated granulocytes, but not with T or B lymphocytes. Some sera also reacted with monocytes and the myeloid cell line, K-562. Tests for antigen-antibody complexes or cold autoantibodies were negative. Although clinical evidence strongly suggests a haptene (drug) mechanism, in vitro mixing experiments were also negative. An alternative choice parallels the model of aldomet-induced Coombs'-positive hemolytic anemia. Finally, GCY first became positive 2-3 mo prior to the onset of AGC on two patients, suggesting the possibility of identifying those at risk well before the onset of neutropenia.

New granulocyte antigens demonstrated by microgranulocytotoxicity assay.

Although granulocyte transfusions and bone marrow transplantation are becoming common clinical modalities, our knowledge of surface nonerythroid, nonlymphoid, non-HLA hematopoetic antigens remains very incomplete. Accordingly, we have systematically screened sera from recipients of multiple granulocyte and whole blood transfusions, and immunoneutropenic patients for antibodies directed primarily at granulocytes. The initial screens demonstrated that >50% of the sera from the above sources contained non-HLA cytotoxic and/or agglutinating antibodies. Preliminary clustering indicated seven possible new specificities detected by microgranulocytotoxicity. Calculations for Hardy-Weinberg goodness of fit based on a study of 98 unrelated donors plus informative families established that 5 of these were alleles of a single new locus termed Human Granulocyte Antigen (HGA)-3a, b, c, d, and e. Absorptions indicated that these antigens were present on mature granulocytes but absent from platelets, lymphocytes, monocytes, and myeloid precursors. A single antigen of another separate locus, HGA-1, was also identified. Absorptions revealed a quite different distribution for HGA-1 than HGA-3, this antigen being detected on monocytes and myeloblasts as well as on mature granulocytes. Independent segregation of the three loci from HLA, from the NA-NB and the 5a-5b antigens, and from themselves was confirmed in informative families.Finally, it seems likely that other antigens will be identified because several other sera that react with both monocytes and granulocytes have been detected.

Mechanisms of levamisole-induced granulocytopenia in breast cancer patients.

Five of 39 (13%) women treated with adjuvant combination chemotherapy plus levamisole immunotherapy after mastectomy for Stage II or III breast cancer developed levamisole-induced granulocytopenia. This complication occurred in each of the women between six and ten weeks after the completion of six months of combination chemoimmunotherapy when they were taking levamisole alone. Although none of the patients had an HLA B-27 locus and leukoagglutinins could not be demonstrated, complement-dependent, IgM mediated, peripheral destruction of granulocytes was documented using a microgranulocytotoxicity assay. In addition, a factor(s) present in serum from patients developing levamisole-induced granulocytopenia caused suppression of bone marrow granulocyte progenitor cells (CFU-C). The possible relationships between levamisole-induced peripheral granulocyte destruction and bone marrow CFU-C suppression are discussed.