Comparative studies of the effects of recombinant GM-CSF and GM-CSF administered via a poxvirus to enhance the concentration of antigen- presenting cells in regional lymph nodes.
Repeated subcutaneous (s.c.) injections of recombinant granulocyte-macrophage colony-stimulating factor (recGM-CSF) for 4-5 days can enrich an immunization site with antigen-presenting cells (APC), which has been correlated with improved immune responses in experimental and clinical studies. A recombinant vaccinia virus encoding the GM-CSF gene (rV-GM-CSF) has been developed and can generate specific antitumour immunity in a whole tumour cell vaccine. In the present study, we examined whether rV-GM-CSF could produce and release GM-CSF locally which, in turn, might enrich a site of immunization for APC as previously shown for recGM-CSF. S.c. injection of rV-GM-CSF significantly (P<0.05) enhanced the percentage and overall number of APC, measured by class II expression levels, in the regional lymph nodes that drain the injection site. Dose- and temporal-dependent studies showed class II expression levels in the draining lymph nodes were maximally enhanced 5-7 days after a single injection of 10(7)plaque-forming units (pfu) of rV-GM-CSF. Flow cytometry revealed that the increase in class II expression resulted from (i) a higher class II expression level on CD19(+)B cells and (ii) an increase in the number of CD11c(+)/class II(+)professional APC within the draining lymph nodes. Moreover, isolation of lymph nodes from rV-GM-CSF-treated mice revealed their capacity to support higher levels of antigen-specific T cell proliferation and allospecific cytotoxic responses. A comparison between a single injection of rV-GM-CSF and a 4-day course of recGM-CSF revealed comparable changes in class II expression and functional T cell assays. GM-CSF can be delivered in a recombinant poxvirus, and the local production of the cytokine results in cellular and phenotypic changes that are similar to those of recGM-CSF. The ability to utilize rV-GM-CSF as a single inoculum may be more compatible with traditional immunization strategies.
Kass
E
E
Laboratory of Tumor Immunology and Biology, National Institutes of Health, Bethesda, MD 20892, USA.
Parker
J
J
Schlom
J
J
Greiner
J W
JW
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D002478:Cells, Cultured; D005260:Female; D005822:Genetic Vectors; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D000949:Histocompatibility Antigens Class II; D016130:Immunophenotyping; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011994:Recombinant Proteins; D014616:Vaccinia virus
D000949:Histocompatibility Antigens Class II; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor