Effect of an Immunomodulatory Pharmacological Agent on the Interaction Between Dendritic Cells and CD4+ T Cells

Begin by adding an immunomodulatory pharmacological agent to immature dendritic cells, or DCs.

DCs express major histocompatibility complex, or MHC class-II molecule and co-stimulatory molecules, crucial for promoting T cell proliferation during immune responses.

The immunomodulatory agent engages with the DC and triggers the downregulation of MHC class-II and co-stimulatory molecules' expression, thereby converting the DC into a tolerogenic dendritic cell or TolDC.

Co-culture TolDCs with naïve CD4+ T cells.

Add an antigenic peptide to the co-culture.

TolDCs internalize the peptide, subsequently processing and loading the resulting antigen onto the MHC molecule.

The antigen-bound MHC molecule translocates to the cell membrane.

Naïve CD4+ T cells interact directly with the antigen-MHC complex on TolDCs.

The interaction with the co-stimulatory molecule on the mature DC enables the full activation of the naïve T cell.

Without co-stimulation, the naïve CD4+ T cell remains dormant and cannot initiate an immune response against the presented antigen.

Resuspend the cells at a 2 x 10⁵ dendritic cells per milliliter concentration, and treat them with the appropriate experimental concentration of the triterpenoid of interest for 1 hour at 37 degrees Celsius.

During the last third of the incubation, resuspend the T cells at a 1 x 10⁷ cells per milliliter concentration and 1 micromolar CFSE for 15 minutes at 37 degrees Celsius. Then, wash the cells with PBS and readjust the volume to a final concentration of 2 x 10⁶ T cells per milliliter.

Co-culture 100 microliters of the treated dendritic cells with 100 microliters of the CFSE-labeled CD4 CD4-positive T cells in each well of a 96-well plate, and add 100 nanograms per milliliter of OVA peptide 322-329 to the cells, measuring the CFSE intensity of the T cells by flow cytometry after 2 to 3 days of incubation.