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Rituximab is a chimeric anti-CD20 antibody of IgG 1 class, with human kappa light-chain constant regions and murine light-and heavy-chain variable regions.CD20 is expressed on mostly all stages of B cell development except the early pre-B-and the antibody producing cell stages.In addition, CD20 surface expression is observed on the surface of most malignant B cells.Clinical trials have indicated that Rituximab is highly effective in treating a wide range of lymphoproliferative disorders including many B-cell lymphomas.Rituximab depletes CD20-positive B cells by different mechanisms of pathways including antibody dependent cellular cytotoxcity (ADCC), complement dependent cytotoxcity (CDC) and induction of direct cell death.Despite the highly effective clinical results seen with Rituximab, some patients with indolent follicular B cell lymphoma remain incurable and characterized by recurrent relapses, and furthermore the response rate is still lower in patients with more aggressive B-NHL.In addition Rituximab is characterized by reduced toxicity, and doesnt overlap with the toxicity of standard chemotherapeutic agents.Therefore, there is a potential reason for combining Rituximab with conventional chemotherapeutic drugs and to develop and establish a new effective strategy in order to improve the clinical outcome of B-Non Hodgkins Lymphoma (NHL) patients.We examined the influence of Hydroxyurea,Vinblastine, and Etoposide commonly used chemotherapeutic agents on the efficiency of Rituximab using Ramos B cell lines.Cell death of such effects was determined and quantified using the Annexin-V/Propidium iodide (PI) detection method in the presence or the absence of caspases inhibitors and analyzed using flow cytometry.Our results have shown that Rituximab efficiency can be improved by the addition of either Hydroxyurea or Vinblastine.However, in contrast to Vinblastine the synergistic effect that initiated by the combination of Rituximab and Hydroxyurea appeared to be caspase-independent.In conclusion, the addition of Hydroxyurea as a single chemotherapeutic agent can synergistically increase Rituximab efficiency against one of the most aggressive types of B cell lymphoma, and that the concurrent use of Rituximab and Hydroxyurea doesnt seem to alter the mechanism by which each individual agent induces cell death.