Immune cytochemical and FISH analyses of monocytes. CD14⁺ cells from a healthy donor (A) and a patient with a deletion of chromosome 7 in the MDS clone (B) were cultured in the presence of HS5 CM for 5 days then spun onto glass slides and labeled with REGA-2D9 monoclonal antibody against MMP-9 revealed with an HRP-conjugated secondary antibody and Vector SG peroxidase substrate. The cells were then probed for chromosome 7 by FISH. Green dots in the nuclei represent the FISH signal of chromosome 7 (indicated by white arrows). Positive staining of MMP-9 is detected as green fluorescence in the cytoplasm as a result of autofluorescence of the peroxidase substrate. Nuclei are counterstained with DAPI (blue). The images were captured and flattened prior to leveling contrast and brightness. Original objective × 100.