Immunohistochemical characterization of Burkitt's lymphoma.

Cytoplasmic immunoglobulins and muramidase (lysozyme) were demonstrated in formalin-fixed tissues by an immunoperoxidase procedure in 3 cases of Burkitt's lymphoma. The Burkitt cells were strongly positive with the full panel of monospecific antisera against human immunoglobulin components (kappa and lambda light chains, gamma, alpha and micron heavy chains). The 'starry-sky' macrophages were weakly positive with antimuramidase antiserum and strongly positive with the antisera against immunoglobulins, thus demonstrating their phagocytic and histiocytic nature. The reasons for the polyclonal increase in immunoglobulins are discussed.