Analysis of natural killer-associated antigens in peripheral blood and bone marrow of multiple myeloma patients and prognostic implications

The aim of this study was to analyse the expression of NK-associated antigens in both peripheral blood and bone marrow lymphocytes from a large series of newly diagnosed multiple myeloma patients. 112 patients with untreated multiple myeloma (MM) were included in the study. 36 sex- and age-matched healthy volunteers were used as controls for peripheral blood (PB) studies and 14 for the bone marrow (BM) studies. Simultaneous stainings with the CD3/CD56, CD2/CD16 and CD8/CD57 monoclonal antibodies were systematically performed in PB and CD3/CD56 and CD2/CD16 in BM in order to analyse their relationship with the clinical and biological characteristics of the disease and survival. The expression of NK-associated antigens (CD56, CD16 and CD57) assessed within the lymphoid gate, was significantly increased (P < 0.001) in the PB of MM patients both in relative and absolute numbers. In the BM a significant increase in the percentage of CD56⁺ lymphocytes (P < 0.001) was also observed; in contrast, the proportion of CD16⁺ cells did not differ significantly from that of normal BM samples. The number of CD56⁺CD3^? lymphocytes increased significantly within high-risk patients (869 ± 671) as compared to intermediate (388 ± 212) and low-risk patients (274 ± 199) (P = 0.04). Moreover, patients with high values of CD56⁺CD3^? lymphocytes showed a statistically significant association with several adverse prognostic factors including anaemia, hypoalbuminaemia, renal failure, high β2M, DNA diploidy and high S-phase plasma cells. In addition, patients with higher absolute numbers of PB CD56⁺CD3^? lymphocytes displayed a poorer prognosis, whereas patients with higher values of CD57⁺CD8^? cells had a better outcome.