Biological Activities of the Lectin, Abrin-a, Against Human Lymphocytes and Cultured Leukemic Cell Lines

The cytoagglutination by abrin-a against human cultured cell lines derived from acute lymphoblastic leukemia (ALL) and human peripheral blood lymphocytes obtained from normal adults and from patients with adult T cell leukemia (ATL) was investigated. Among acute T lymphoblastic leukemia (T-ALL) cell lines, abrin-a showed strong cytoagglutination against relatively differentiated cell lines, such as Jurkat and CCRF-HSB-2. Among acute B lymphoblastic leukemia (B-ALL) cell lines, abrin-a strongly agglutinated an immature cell line, NALM6. In comparison with ALL cell lines, cytoagglutination by abrin-a against normal lymphocytes was weak. Abrin-a showed higher cytoagglutination against lymphocytes derived from ATL than lymphocytes derived from normal adults. In connection with the cytoagglutination, abrin-a-induced cytotoxicity against human cultured leukemic cell lines was evaluated. In proportion to the extent of cytoagglutination, abrin-a induced cytotoxicity in Jurkat, CCRF-HSB-2, MOLT-4, RPMI8402, and BALL-1 as well. Although CCRF-CEM and BALM-1 were both weakly agglutinated by abrin-a, these cell lines were very sensitive to the abrin-a-induced cytotoxicity. NALM6 was strongly agglutinated by abrin-a, but abrin-a exhibited less strong cytotoxicity against this cell line. These results suggest the feasible application of abrin-a as a tool to distinguish the human leukemic cells and its potential for clinical application.