| Being a bridge of antigen stimulus to immune response and playing an important role in induction of special immune response, the antigen presentation process is a chief factor of immunoreaction. Degree of immune response of organism to antigen is not only relative to the character of antigen and the quality of immune effector cells, but also the antigen presentation role closely. As the executors of antigen presentation, the function of presentation cells are specially more important. With an unspecific effector function, macrophages are also a kind of important antigen presentation cells. Now, approaches of monocytes/macrophages generation from blood circulation and activation in vitro are being perfected, and clinical studies in the field of adoptive immunotherapy of tumor with activated monocytes/macrophages have made progress to a certain degree. Up to now, most of the studies on the antitumor capacity of macrophages focused on the augmentation of their unspecific cytotoxic activity but ignored their antigen presenting ability. Considering undividing cells might be transfected with adenovirus vector and macrophages could be activated by IL-2, we transfected mIL-2 gene into the freshly isolated peritoneal macrophages with recombinant adenovirus, and pulsed with tumor antigen in vitro, in order to enhance the immune effector function as well as the antigen presentation function simutaneously, and acquired more effective actions of antitumor. X-gal staining showed that the freshly isolated peritoneal macrophages could be transfected effectively (up to 90%) by the replication defective adenovirus bearing LacZ gene. High levels of IL-2 could be detected in the supematant of macrophages 4 hours after gene transfer, The dynamic secretion of IL-2 steadily continued for more than 10 days. Further exploring for the changes of effector function and antigen presentation function of gene-transfected macrophages in vitro indicated that the cytotoxicity and the antigen presenting ability of macrophages were enhanced significantly after IL-2 gene transfection. The level of nitric oxide (NO)-unspecific tumoricidal molecules secreted by gene-transfected macrophages was expectedly high, and the production of NO reach the top value 36 hours later; but a little of TNF-a, IL-I in the 3 supernatant of gene-transfected macrophages could only be detected respectively in point of 24~ 36 hour after transfection. The TNF-a, IL-i and especially NO in the supernatant of gene-transfected macrophages were determined to elucidate the possible mechanisms of the increased cytotoxicity. Results of FACS assay showed that among the several of antigen presentation-associated molecules on macrophages surface, such as Ia, H-2, ICAM-l, B7-l, B7-2, CD4O etc., the expression of Ta, B7-l, B7-2, CD4O molecules on IL-2 gene-transfected macrophages increased, and H-2, ICAM-l had no change. This was confirmed by antibody (anti-Ia, B7-l, B7-2, CD4O) alone or combined blocking test which decreased antigen presentation markedly. These results suggested that the increased antigen presenting function might be correlated to the increased levels of Ia, B7- 1, B7-2 and CD4O, and as first and important secondary signal in the process of presenting antigen, these surface molecules interacted as well as increased reciprocally. Additionally, the primary observation upon the optimal pulsing scale and time showed when macrophages pulsed with tumor antigen five times to macrophages and incubated for 4...
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