Unusual Phenotype (Leu 7+, OKT4+, OKMl+) Expressed by Cells from a Patient with an Abnormal Expansion of Granular Lymphocytes

We report the case of a 70-year-old female with a lymphocytosis which was casually detected during a routine examination. Immunological studies revealed the expansion of granular lymphocytes (GL) with the following, previously undescribed phenotype: Leu 7+, OKT3+ , OKT4+, OKT8-, OKM1+ . These cells were tested for their functional activities and found to exert neither helper nor suppressor functions in in vitro tests. Cytotoxic activities demonstrated a strong ADCC and a markedly reduced NK function. 1 year later the clinical course has remained good without any treatment and we suggest that this case should be classified as an abnormal expansion of GL, despite the OKT4 positivity of the cells. Our data point out the importance of a careful immunological study of cells from these rare patients and suggest the existence of a normal GL population expressing the OKT4 phenotype, which is possibly expanded in this patient.