Clonal Populations of T-Cells in Patients with B-Cell Malignancies

Abstract

Patients with B-cell malignancies are often immunosuppressed and have defective T-cell function in vitro. In addition they frequently have unusual T-cell populations in the peripheral blood including an increase in the number of activated T-cells and an inverted CD4:CD8 ratio. More recently several reports have documented the presence of large, monoclonal populations of T-cells in patients with paraproteinaemia, B-CLL and hairy cell leukemia. Such cells can reach very high levels in the peripheral blood, occasionally representing over 50% of all CD8⁺ T-cells. These clonally expanded cells have a characteristic morphology and phenotype in that they are often large, granular cells with natural killer cells markers. Their properties have not been studied in detail but they appear to suppress immunoglobulin production and kill cell targets in an MHC-unrestricted manner. The relationship of clonal T-cells to the B-cell tumour is unclear. They may be directly interacting with the malignant clone or alternatively be non-specifically activated secondary to a disruption of the immune homeostasis by tumour cells. If they indeed represent an attempt by the immune response to control the malignant cells it is possible that they may be utilised in future attempts at immunotherapy.

Key Words:

• Clonal - cells
• leukemia
• CD4⁺ CD8⁺ T-cells