Heterogeneity of chronic T-cell lymphocytosis: immunological and clinical aspects.

The clinical and laboratory findings as well as the immunological cell phenotype of nine patients with chronic T-cell lymphocytosis (T-CL) are presented. The clinical course was stable in most patients and only one patient died. Splenic enlargement was the main clinical finding and in contrast to B-CLL the age at presentation was lower; T-CL predominated in females and lymphadenopathy was rare. The lymphocyte count was moderate (range 4.1-23.8 X 10(9)/L). Six patients displayed neutropenia; in contrast, anaemia was only observed in one patient and thrombopenia in another. The immunological cell phenotype was heterogeneous: four cases exhibited a cytotoxic/suppressor phenotype, two a helper phenotype and in the remaining three cases mixed OKT4+ and OKT8+ lymphocytes were observed; these results suggest that T-CL may originate from different T-cell subsets. Although the question of the benign or neoplastic nature of the T-CL remains open, some of the characteristics of the immunological phenotype could provide additional evidence to demonstrate the malignant condition of the process: in contrast to normal lymphocytes (CD5+, CD7+) the lymphocytes in T-CL were generally CD5 +/-, CD7-, and one patient showed an aberrant phenotype (OKT3+, OKT6+), an occasional finding in other T lymphoproliferative disorders.