Effect of Myeloma-Derived Microparticles on in Vitro Proliferation and Viability of Alloimmune Human Peripheral Blood Mononuclear Cells

Microparticles (MPs) are small vesicles released from the cell membrane. Accordingly, these contain active molecules to mediate biological processes, including cell proliferation and cell cycle progression. The fusion of myeloma cell lines with immunized B lymphocytes is a critical step of hybridoma technology. MPs modulate lymphoproliferation, thereby facilitating B cell expansion and successful immortalization. Human alloimmune B cells are considered valuable sources of monoclonal antibodies, and peripheral blood is a pool of B lymphocytes. The present study aimed to investigate the role of myeloma-derived MPs in the proliferation of alloimmune peripheral blood mononuclear cells (PBMCs).

In the current experimental study, ultracentrifugation isolated MPs from three different myeloma cell lines, including U266, P3x63Ag8, and SP2/0. PBMCs were extracted from the whole blood of a patient with thalassemia alloimmune exposed to MPs. Thereafter, both the proliferation and cell viability were evaluated using inverted microscopy and the trypan blue staining method.

MPs derived from the P3X63Ag8 myeloma cell line were shown to have the most effects on cell proliferation and viability (p=0.0005). MPs of the SP2/0 cell line initially increased the proliferation of PBMCs, but viable cells were drastically reduced in the following weeks. As well, U266 cell-derived MPs increased the proliferation of PBMCs (p=0.0001), but it was half of the group receiving P3x63Ag8 derived MPs. However, the viability of treated cells remained almost constant for 5-weeks.

Altogether, the obtained data indicated that P3X63Ag8 and U266 derived MPs could increase the viability of PBMCs. If the complimentary examination is confirmed, these MPs could also be used as the potential agents in B lymphocyte proliferation, thereby helping in immortalization and antibody production.