USEFULNESS OF A NEW CD5 ANTIBODY FOR THE DIAGNOSIS OF T-CELL AND B-CELL LYMPHOPROLIFERATIVE DISORDERS IN PARAFFIN SECTIONS

We used a new antibody (NCL-CD5-4C7) immunoreactive for CD5-positive c ells in paraffin-embedded tissue, with the microwave antigen retrieval method, to analyze a number of well-characterized cases of B-cell and T-cell non-Hodgkin's lymphomas whose CD5 immunoreactivity was documen ted by immunohistochemical analysis performed on frozen sections and/o r now cytometric immunophenotypic analysis of neoplastic cell suspensi ons, In all of the cases included in the study, small, reactive T lymp hocytes within histologic sections were strongly positive for CD5 and served as an internal positive control, All CD5-positive T-cell non-Ho dgkin's lymphomas (13 [100%] of 13) from several histologic subgroups, were immunoreactive for CD5 in paraffin sections, although 4 of 13 ex hibited weak or limited staining of neoplastic cells, The majority of cases of B-cell small lymphocytic lymphoma/chronic Iymphocytic leukemi a (SLL/CLL) (13 [81%] of 16) and mantle cell lymphoma (14 [93%] of 15) , both B-cell lymphoproliferative disorders that are immunoreactive fo r CD5, were immunoreactive for CD5 in paraffin sections, although 5 of 13 cases of SLL/CLL and 6 of 14 cases of mantle cell lymphoma exhibit ed weak and/or limited staining of neoplastic cells, Other B-cell non- Hodgkin's lymphomas of various subtypes, including marginal zone, foll icular, diffuse large cell, and lymphoblastic types, were nonreactive for CD5 in paraffin sections, as expected, CD5 antibody NCL-CD5-4C7 sh ould be useful for the routine characterization of suspected T-cell an d B-cell lymphoproliferative disorders when only paraffin-embedded tis sue is available for immunophenotypic analysis.