Recognizes proteins of 21-24kDa, identified as the A and B subunits of S-100 protein. S-100 belongs to the family of calcium binding proteins such as calmodulin and troponin C. S-100A is composed of an alpha and beta chain whereas S-100B is composed of two beta chains. Antibody to S-100 stains Schwannomas, ependymomas, astrogliomas, almost all benign and malignant melanomas and their metastases. S-100 protein is also expressed in the antigen presenting cells such as the Langerhans cells in skin and interdigitating reticulum cells in the paracortex of lymph nodes. The diagnosis of Histocytosis X is confirmed by S-100 staining. This antibody is excellent for immuno-histochemical staining of formalin-fixed, paraffin-embedded tissues. S-100 protein is highly solouble and may be eluted from frozen tissue duing staining