Demonstration of distinct antigenic profiles of small B-cell lymphomas by paraffin section immunohistochemistry

The immunoperoxidase technique was used with antibodies against B-cell-asso ciated antigens, including CD20, CD79a, CD10, CD23, CD43, cyclin D1, bcl-2, and kappa and lambda immunoglobulin light chains on formalin-fixed and B5- fixed tissue sections of follicular, small lymphocytic, mantle cell, and ma rginal zone lymphomas. Results obtained with paraffin section immunohistoch emistry for CD20, CD10, CD23, and kappa and lambda light chains were compar ed with results obtained with flow cytometry or frozen section immunohistoc hemistry. Cells in all of the lymphoma types were positive for CD20 and CD7 9a. The antigenic profiles of the B-cell lymphomas demonstrated in paraffin sections were lymphoma type distinctive. Intrafollicular lymphocytes in fo llicular lymphomas were positive for CD10 and bcl-2. Small lymphomas were p ositive for CD10 and bcl-2. Small lymphocytic lymphomas expressed CD43 and CD23 and were negative for CD10 and cyclin D1. Mantle cell lymphomas charac teristically expressed CD43 and cyclin D1 and were negative for CD23 and CD 10. Marginal zone lymphomas were negative for CD23, CD10, and cyclin D1. Al l of the antibodies performed better in B5-fixed tissues, but formalin-fixe d tissue immunophenotypes were always similar to those obtained on the B5-f ixed tissue. These results were possible using well-fixed tissue, various a ntigen retrieval strategies, paraffin section reactive primary antibodies, and sensitive detection systems. Paraffin section immunohistochemistry on s ections of routinely fixed tissue can be used similarly to flow cytometry a nd frozen section immunohistochemistry when classifying the lymphomas of sm all B lymphocytes.