AN IMMUNOHISTOLOGICAL STUDY OF HUMAN LYMPHOMA

Abstract

The problems encountered in staining immunoglobulin (Ig) in sections of paraffin-embedded human lymphoma samples were investigated. The masking of cytoplasmic Ig, which occurs when tissues are fixed in formol saline (the fixative employed in most previous studies), can be avoided by the use of mercury-based fixatives. When non-Hodgkin''s lymphoma samples fixed in this way were studied it was found that cytoplasmic Ig labeling of lymphoid and histiocytic cells is often attributable to non-specific uptake of serum proteins. This phenomenon probably accounts for a number of published anomalous immunoperoxidase staining results in human lymphoma (e.g., the presence of .kappa. and .lambda. chains in the same neoplastic cell). Double immunoenzymatic labeling (using alkaline phosphatase and peroxidase) proved valuable in the elucidation of this phenomenon. When staining due to absorbed Ig was discounted it was possible to demonstrate monoclonal Ig labeling in 7 of 16 cases of non-Hodgkin''s lymphoma. In each case IgM was found in association with a single L chain type and these results were in agreement with those obtained by direct immunofluorescent labeling of cryostat sections. In a further case .mu. chains without associated L chains were demonstrated by immunoperoxidase staining. Seven cases of Hodgkin''s disease were studied by immunoenzymatic techniques. Although IgG was frequently found in Reed-Sternberg and Hodgkin''s cells its presence was not attributable to non-specific uptake of serum protein since albumin was absent or only present in small amounts. These findings are in support of the macrophage origin of these cells.