Improved detection of lymphoid cell surface antigens in tissues fixed in periodate-lysine-paraformaldehyde (PLP)

Stabilization of cell surface antigens and preservation of tissue morphologic characteristics are important for diagnostic immunologic studies. Current reports continue to regard unfixed frozen sections as the material of choice for immunoperoxidase studies of lymphoproliferative diseases. In this study, periodate-lysine-paraformaldehyde (PLP) is shown to be a valuable fixative for the improved detection of surface antigens in lymphoid tissue. In cases of non-Hodgkin's lymphoma and Hodgkin's disease, more frequent detection of diagnostic markers and ease of interpretation was demonstrated by use of PLP-fixed frozen tissue as compared with unfixed frozen tissue. Immunoglobulin staining was more easily interpreted in 30% of B-cell non-Hodgkin's lymphoma. In Hodgkin's disease, Ki-1 antigen, a diagnostic marker of Reed-Sternberg cells, was found in PLP-fixed tissue from two cases in which this antigen was not detected in corresponding unfixed frozen tissue. The authors have demonstrated that PLP-fixed tissue can be sent to a central reference laboratory at ambient or room temperature, avoiding the expense and inconvenience of transporting specimens on dry ice. The authors conclude that PLP fixation is the preferred method for immunopathologic study of human lymphomas.