Acquired (adaptive) immunity is demonstrated through the immune function of T lymphocytes and B lymphocytes, including CD8+ cytotoxic T cells that are the effector cells that can destroy tumor cells, CD4+ helper T cells that regulate CD8+ T-cell and B-cell function, and B cells that present antigen and can become plasma cells which produce antibodies.
Immune checkpoints are mostly expressed on T cells. A good experimental approach to assess the function of anti-immune checkpoint antibodies is via stimulation of primary T cells or PBMCs. Blocking the binding between inhibitory immune checkpoints and their ligands can activate the immune response of T cells. Stimulation of co-stimulatory immune checkpoints by agonist antibodies can enhance the immune response of the T cells. To date, GenScript Probio has successfully developed a primary cell-based in vitro bioassay platform for anti-immune checkpoint antibodies.
GenScript Probio provides a variety of immune cell stimulation assays to accommodate your research needs. There are many types of stimuli for this assay to choose from, including non-specific ones such as PHA, PMA, bacterial lipopolysaccharide (LPS), staphylococcal enterotoxin (SEA, SEB, SEE, etc.), anti-CD3 antibody, and anti-CD3/CD28 beads, as well as specific stimuli such as cytokines. By assessing immune cell proliferation, single or multiplex cytokine release, or expression of immune cell activation markers, the potency and efficacy of the antibody drug candidates can be evaluated.
Figure: Mechanism of actions for immune co-stimulatory and inhibitory immune checkpoints in tumor microenvironment
Mixed lymphocyte reaction (MLR) uses PBMCs from two different donors and co-culture them in vitro. Because the HLA-II antigen D and DP on the cell surface from two donors are different, they may stimulate each other's lymphocyte to proliferate or to release cytokines such as IL-2 and IFN-γ. We can evaluate the function of anti-immune checkpoint antibody drugs by assessing the amount of cytokines being released.
Figure: Mechanism of Action of MLR
Figure 1.: Reproducibility of MLR assay data (Pembrolizumab as positive control, human IgG4 and murine IgG1 as negative controls)
Figure 2.: Bioactivity comparison of anti-PD-1 antibody (Pembrolizumab, Nivolumab) and anti-PD-L1 antibody (MPDL3280A) in MLR assay