Institute of Biotechnology, Sun Yat Sen University of Medical Sciences, Guangzhou and ^*Institute of Molecular Immunology, First Military Medical University, Guangzhou, China

The study overcame the problems of weakly immunogenic granulocyte colony-stimulating factor (G-CSF) to mouse by utilizing the typhoid bacteria body to produce 3 murine hybridoma clones of monoclonal antibodies against recombinant human G-CSF. The 3 hybridoma clones were named 1H₁₁, 2B₃ and 2C₃. These antibodies were all IgG2a. Western blot was applied to test the specificity of antibodies against G-CSF. The McAb additivity test and McAb competitive test showed the 2B₃ and 2C₃ recognized the same epitope of G-CSF while 1H₁₁ recognized the other epitope of G-CSF. The neutralization trial of G-CSF indicated 2B₃ and 2C₃ were capable of negating the proliferative activity of G-CSF in NFS-60 cells. The double antibody sandwich ELISA was established by using these McAbs to detect G-CSF levels in human serum. The sensitivity to G-CSF was 340 pg/ml. G-CSF levels of human serum samples were also evaluated. It was found that no positivity was encountered in normal serum samples. However, G-CSF was detected in 91.6% of patients with bacterial infection and in 25-35.7% of leukemia patients. The study provided a simple, rapid and specific assay of G-CSF in human serum. The assay overcame the flaw of myeloid progenitor cell assay and NFS-60 cell assay, which were tedious and time-consuming.