Development of a Mixed Lymphocyte Reaction assay for evaluating the allogenicity of cell therapy products

Cell therapies represent a promising class of treatments with the potential to address many incurable diseases through diverse and powerful mechanisms of action. In contrast to autologous cell therapies, which utilise cells derived from the patient, allogeneic cell therapies offer the advantage of being potential "off-the-shelf" treatments. 

However, the use of allogeneic products require in large extent HLA-compatible donors, to extend potency and improve product safety and tolerability. Consequently, both the FDA and EMA mandate specific tests to demonstrate the allo-compatibility of allogeneic treatments.

The Mixed Lymphocyte Reaction (MLR) is an in vitro assay used to detect and measure allogeneic responses by cell proliferation and cytokine production. We present a nonradioactive flow cytometry method efficiently assessing lymphocyte proliferation upon non-specific T cell stimulation and allogeneic recognition between randomly selected PBMCs isolated from healthy donors. Orthogonal methods were also developed to detect pro-inflammatory cytokine secretion as a surrogate of allogenicity, using immunoassay techniques such as Gyrolab, Luminex or ELISA. 

As a proof-of-concept, we characterised the allogeneic recognition of cell therapy products (CTPs), which are employed as regenerative therapy candidates, by co-culturing them with PBMCs from various healthy donors.