CLONAL POPULATIONS OF T-CELLS IN PATIENTS WITH B-CELL MALIGNANCIES

Patients with B-cell malignancies are often immunosuppressed and have defective T-cell function in vitro. In addition they frequently have u nusual T-cell populations in the peripheral blood including an increas e in the number of activated T-cells and an inverted CD4:CD8 ratio. Mo re recently several reports have documented the presence of large, mon oclonal populations of T-cells in patients with paraproteinaemia, B-CL L and hairy cell leukemia. Such cells can reach very high levels in th e peripheral blood, occasionally representing over 50% of ail CD8(+) T -cells. These clonally expanded cells have a characteristic morphology and phenotype in that they are often large, granular cells with natur al killer cells markers. Their properties have not been studied in det ail but they appear to suppress immunoglobulin production and kill cel l targets in an MHC-unrestricted manner. The relationship of clonal T- cells to the B-cell tumour is unclear. They may be directly interactin g with the malignant clone or alternatively be nonspecifically activat ed secondary to a disruption of the immune homeostasis by tumour cells . If they indeed represent an attempt by the immune response to contro l the malignant cells it is possible that they may be utilised in futu re attempts at immunotherapy.