Quantitation of immunogold labeling

Most of the published, quantitative immunogold labeling studies do not reflect the true concentration of antigen in a given cell compartment. Presently, the majority of the data on labeling density provides a potential way to follow the distribution of antigens, but does not indicate the quantitative concentration of the antigen present. The majority of the published quantitative data is semiquantitative. Ideal quantitative data must relate the intensity of the immunoreaction to the concentration of the underlying antigen population. Since this requirement is not fulfilled by most of the available methods, caution is warranted in interpreting the immunogold quantitative data. The difficulty in obtaining reproducible quantitative data is also due to the fact that preparatory procedures are quantitatively unknown parameters with respect to quantitative immunogold postembedding and preembedding labeling.