Immunocytochemistry as a diagnostic tool.

ICC is a powerful technique to gain information about pathological processes in peripheral nerve beyond the limits of classical histopathology. ICC can aid in the identification of cellular infiltrates (T cells, B cells and macrophages), in the definition of their state of activation (MHC class I and II molecule expression), in the localization of cellular adhesion molecules (vascular and intercellular adhesion molecule 1) involved in trafficking of inflammatory cells through the endothelium and, finally, in the identification of locally produced cytokines (interferon gamma, interleukins and tumour necrosis factor). Moreover, ICC can identify pathological deposits, such as immunoglobulins and amyloid, within nerves and can be used to study the expression of myelin sheath proteins as they change in disease. In this chapter, basic immunocytochemical findings in experimental diseases of the peripheral nervous system, such as WD and immune-mediated demyelination, are summarized and discussed in the context of similar observations in sural nerve biopsies.