Dendritic Cells Generated in the Presence of Platelet Lysate Have a Reduced Type 1 Polarization Capacity

ABSTRACT

Previously, we have shown platelet lysate (PL) can be used as a non-xenogeneic serum supplement for generation of monocyte-derived dendritic cells (DCs). Since DC-based activation protocols are extremely sensitive to microenvironmental changes such as replacement of culture medium, we wanted to examine the behavior of DCs cultured in the presence of PL under various type-1 activation conditions and assess their type 1 polarization capacity. We compared the quality of DCs cultured in 10% PL-supplemented RPMI medium (plDCs) with clinical-grade DCs obtained using commercially available serum-free medium (sfDCs), frequently used in established DC vaccine protocols. The DC maturation protocols consisted of either monophosphoryl lipid A/IFN-γ, poly I:C/TNF-α/IFN-α or poly I:C/R848. In general, plDCs were inferior to sfDCs in most aspects of their functional type 1 polarization characteristics. After maturation, the expression of co-stimulatory, HLA class II and lymph node-homing molecules was strongly up-regulated, with some noticeable differences. The expression of CD80 and CD86 was more extensive on plDCs, which was particularly evident in case of CCR7. However, after observing their functional capacity, plDCs had significantly lower allo-stimulatory capacity both in terms of CD4⁺ and CD8⁺ T cell stimulation. The high expression of CCR7 corresponded to higher CCL-19 directed DC migration of plDCs compared to sfDCs. Finally, their capacity to induce granzyme B and IFN-γ production in CD8⁺ T cells was significantly reduced in comparison to sfDCs. Based on these findings, the use of PL as an alternative serum supplement for generation of monocyte-derived DC anti-tumor vaccines is questionable.

Abbreviations: Ag: antigen; CCL: chemokine ligand; CCR: chemokine receptor; DC: dendritic cells; DC-SIGN: dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin; FBS: fetal bovine serum; GMP: good manufacturing practice; IFN: interferon; IL: interleukin; MPLA: monophosphoryl lipid A; PGE: prostaglandin E; pI:C: polyinosinic:polycytidylic acid; pl: platelet lysate; sf: serum free; TLR: toll-like receptor; TNF: tumor necrosis factor.

KEYWORDS:

• Dendritic cells
• platelet lysate
• cancer vaccines
• serum-free media
• GMP protocols

Acknowledgments

The authors would like to thank dr. Tina Cirman for assistance in preparation of platelet lysate.

Author’s contributions

N.T., I.P.S. and K.P. performed in vitro cellular assays. P.R. assisted in writing the manuscript. U.Š. designed the experiment and wrote the manuscript.

Availability of data and material

N/A.

Competing interests

None.

Consent for publication

N/A.

Declarations

Ethics approval: Buffy coats from healthy volunteers were obtained according to institutional guidelines and with permission issued by the National Medical Ethics Committee under reference number 0120-279/2017-3.

Additional information

Funding

This research was funded by the Slovenian Research Agency, grant no. P3-0371;Javna Agencija za Raziskovalno Dejavnost RS [P3-0371].