A Research about Hyperthermia Effected On RPMI-8266 Multiple Myeloma Cells in Order to Enhance the Cytotoxicity of NK Cell.

To compare the cytotoxicity of NK cells on RPMI-8266 multiple myeloma cells before and after thermotherapy, and to explore its mechanism.

RPMI-8226 cell was heated for 2 hours at 42°C and after continous culturing for 48 hours, remove dead cells at lower-speed centrifugation. Detected cytotoxicity of NK cells against RPMI-8226 cells, combinig with or without thermotherapy, by LDH releasing assay at different effect-to-target cell ratios (E:T). Moreover compare the expression of HLA class I molecules and NKG2D ligands-MHC class I chain-related molecule A or B and human cytomegalovirus glycoprotein UL16 binding proteins, ULBPsFULBP1AULBP2AULBP3 on the surface of RPMI 8226 cells were analyzed by flow cytometry.

As for E:T is 5:1, the cytotoxicity of NK cells combining with or without hyperthermia on the 8266 NK cells are (2.15 ± 0.32)% and (9.32 ± 1.27)% respectively; at E:T(10:1), cytotoxicities are (5.26 ± 0.84 )% and (20.37 ± 1.78)%; at E:T (20:1), they are(7.63 ± 1.05)% and (28.69 ± 2.25)%;at ET(40:1), they are (10. 18 ± 1.53)% and (35.64 ± 4.87)%. At the different target ratio, the cytotoxcity of NK cells combining with or without thermotherapy were significant statistical difference (P <0.05). Before hyperthermia, the expression of MICA, MICB, ULBP1, ULBP2 and ULBP3 cell surface molecules on RPMI-8266 is (2.82 ± 0.37)%, (6.74 ± 1.16)%, (3.26 ± 2.41)%, (5.42 ± 1.58)%, (5.72 ± 1.66)%; After hyperthermia, (3.18 ± 0.72)%, (7.83 ± 0.96)%, (19.77 ± 4.28)%, (5.23 ± 1.48)%, (21.42 ± 4.68)% respectively; before and after hyperthermia, all of RPMI-8266 cell surface NKG2D ligands were significant statistical significance (P <0.05). Before and after hyperthermia, the expression of 8266 cell surface HLA -± cell surface molecule were (92.25 ± 6.46)%, (89.38 ± 7.87)%; The difference between the two groups was no significant statistical significance (P> 0.05).

Hyperthermia can enhance cytotoxicity of NK cells on multiple myeloma RPMI-8266 cells through upregulating the expression of NKG2D ligand ULBP1 and ULBP3 molecule on RPMI-8266, while no effect on HLA ± molecules.

No relevant conflicts of interest to declare.