Proportional and functional anomalies of CD38+ NK Cells:A new mechanism for impaired anti-tumour immunity in multiple myeloma?

Background

The abnormal quantity and dysfunction of immune cells in patients with multiple myeloma impede anti-tumour immunity and prompt the occurrence and development of disease. It has been reported that CD38⁺ NK cells are involved in immune regulation.

Methods

Peripheral blood (PB) samples were collected from healthy volunteers (HV) and newly diagnosed multiple myeloma (NDMM) patients. The proportions of CD38⁺ NK cells and CD38⁺CD16⁺ NK cells were measured. Moreover, CD38⁺ NK cells separated from PB were co-cultured with RPMI-8226 assess their impact on myeloma cell apoptosis and proliferation. Similar co-culture experiments were also initiated with naive CD4⁺ T cells from HV to ascertain the influence of CD38⁺ NK cells on regulatory T cells (Tregs) differentiation.

Results

The percentages of CD38⁺ NK and CD38⁺CD16⁺ NK cells in the PB of NDMM patients were markedly decrease than that in HV. The apoptosis rate of RPMI-8226 was slightly increased following co-culture with CD38⁺ NK cells from NDMM samples, as opposed to those from HV samples. CD38⁺ NK cells from NDMM or HV had similar inhibitory effect on MM cell proliferation. Furthermore, CD38⁺ NK cells from NDMM fostered CD4⁺ T cell differentiation to Tregs more than those from HV.

Conclusion

In MM, the proportion and function of CD38⁺ NK cells undergo changes, which may be related to the formation of the immunosuppressive microenvironment.