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Clinicopathological and phenotypic features of chronic NK cell lymphocytosis identified among patients with asymptomatic lymphocytosis
Author(s) -
Cao F.,
Zhao H.,
Li Y.,
Dai S.,
Wang C.
Publication year - 2015
Publication title -
international journal of laboratory hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.705
H-Index - 55
eISSN - 1751-553X
pISSN - 1751-5521
DOI - 10.1111/ijlh.12410
Subject(s) - lymphocytosis , asymptomatic , immunology , immunophenotyping , natural killer cell , medicine , biology , pathology , flow cytometry , cytotoxic t cell , in vitro , biochemistry
Summary Introduction Chronic natural killer ( NK ) cell lymphocytosis is currently a provisional entity. This study demonstrated NK cell lymphocytosis in patients with asymptomatic lymphocytosis and presented the hematological and phenotypic findings. Methods Flow cytometry analysis was performed for investigation of unexplained peripheral lymphocytosis. NK cells were determined by the phenotype of CD 3−/ CD 16+/ CD 56+. Chronic NK cell lymphocytosis was defined by a NK cell count of ≥2 × 10 9 /L, persistent for over 6 months, no evidence of B ‐ or T ‐cell clonality and no hematologic disorders. Results Among 190 patients with peripheral lymphocytosis, 15(7.9%) patients, age 42–72 years, were identified to have NK cell lymphocytosis, with a median NK cell count of 3.1 × 10 9 /L (range 2.1–7.3 × 10 9 /L). Persistent NK cell lymphocytosis was confirmed with a median follow‐up of 18 months. CD 56 bright NK cell populations were seen in eight patients and CD 56 dim NK cells in seven patients. CD 57 co‐expression was seen in both CD 56 dim and CD 56 bright cells. CD 7, CD 2, or CD 8 expression was seen in some of the NK populations. The NK cell lymphocytosis appeared stable and no progression to NK cell leukemia during the follow‐up period. Conclusion This study demonstrated that chronic NK cell lymphocytosis, similar to monoclonal B lymphocytosis or T‐cell clones, may account for asymptomatic lymphocytosis. There were no identifiable causes of the NK cell expansion. The variable phenotype may represent the heterogeneity and pathological features of NK lymphocytosis.