An immunologic approach for the detection of tumor cells in the peripheral blood of patients with malignant lymphoma; implications for the diagnosis of minimal disease.

Lymphocytes were isolated from infiltrated lymph nodes and blood of eight patients with malignant lymphocytic lymphoma. All patients had normal numbers of circulating lymphocytes with normal morphology. None of the patients had serum paraproteins. The isolated lymphocytes from patients and controls were stained with affinity purified antibody specific for kappa- or lambda-light chains and analyzed by using a fluorescence activated cell sorter. Cells from infiltrated nodes stained for only one light chain type at high levels of fluorescence intensity. An increase in the number of brightly stained cells bearing the light chain type found in the involved node was readily detected in the peripheral blood of all but one of the patients with lymphoma. Similar changes in the ratio of kappa+- to lambda+-cells were not observed in 41 samples from nomral individuals and patients with other diseases.