Quantification of Proliferating Human Antigen-specific CD4⁺ T Cells using Carboxyfluorescein Succinimidyl Ester

Presented here is a protocol for measuring proliferating CD4⁺ T cells in response to antigenic proteins or peptides using dye dilution. This assay is particularly sensitive to rare antigen-specific T cells and can be modified to facilitate cloning of antigen-specific cells.