[Immunodetection of gastrin-like peptides in routine electron microscopy by the "immunogold" method]

The present immunoelectron microscopic study was carried out in order to evaluate the influence of several technical parameters of the immunogold staining procedure on the labelling intensity of gastrin-storing cells in normal and pathological states. Ultra-thin sections of double-fixed Epon embedded human pyloric mucosa were immunolabelled using a C-terminal directed antigastrin serum, followed by colloidal gold linked immunoglobulins. When the labelling density occurring over the endocrine secretory granules was quantitatively evaluated, the following conclusions could be drawn: the density increased dramatically when particles of decreasing diameter (40 nm, 20 nm, 10 nm) were comparatively used, the dilution of the primary antiserum had to be adjusted in order to obtain an intense specific labelling together with a negligible background (non specific) labelling. However, a long incubation time of the primary antiserum, as well as the use of etching procedures, resulted in an increase of the labelling density when a highly diluted antiserum was applied. Subsequent attempts to immunolabel ultrathin sections of gastrin-secreting malignant tumours showed that the goal could be achieved on tissues routinely processed for electron microscopy, provide the previous parameters were carefully selected according to the control G cell model.