Immunostaining for leukocyte common antigen using an amplified avidin-biotin-peroxidase complex method and paraffin sections. A study of 735 hematopoietic and nonhematopoietic human neoplasms.

Antibodies to leukocyte common antigen (LCA) are valuable in surgical pathology in the diagnostic separation of malignant lymphomas from poorly differentiated neoplasms of other types. However, several publications have reported difficulty in obtaining adequate LCA labeling in paraffin-embedded specimens. To assess this problem further, we applied an amplified version of the avidin-biotin-peroxidase complex procedure to 315 formaldehyde-fixed hematopoietic malignancies, and 420 nonhematopoietic tumors that had been similarly processed. All non-Hodgkin's lymphomas were LCA-reactive with this method, whereas none of the nonhematopoietic neoplasms were stained. Twelve of 25 cases of Hodgkin's disease displayed LCA-positivity in Reed-Sternberg cells, but all contained reactive, benign inflammatory cells. Hence, the specificity of the amplified anti-LCA/avidin-biotin-peroxidase technique was 100%, and its sensitivity was 96%. This procedure should allow surgical pathologists to obtain reliable, reproducible staining of hematopoietic neoplasms in paraffin-embedded tissues.