Effect of several fixatives on the density of concanavalin A binding sites of murine peritoneal macrophages determined by fluorescence microscopy and X-ray microanalysis.

The influence of various fixatives (glutaraldehyde, formaldehyde, OsO4) on the retention of antigenicity of peritoneal macrophages was studied by means of fluorescence microscopy, scanning electron microscopy, and X-ray microanalysis. After fixation with formaldehyde the Concanavalin A (Con A) binding sites were found to be highest, whereas the fixation with OsO4 results in loss of many binding sites. The fluorescence microscopic investigations of glutaraldehyde fixed cells is impaired by fixative induced fluorescence. Therefore X-ray microanalytical determinations show better results for these cells than fluorescence microscopic measurements. On contrary to direct labelling method the number of unspecific Con A binding sites on peritoneal macrophages labelled with the sandwich method is negligible.