CTL used four-colour ImmunoSpot® assays, in conjunction with peptide pools that cover the sequence of tyrosinase (Tyr), melanoma-associated antigen A3 (MAGE-A3), melanocyte antigen/melanoma antigen recognised by T-cells 1 (Melan-A/ MART-1), glycoprotein 100 (gp100) and New York esophageal squamous cell carcinoma-1 (NY-ESO-1) to characterise the melanoma antigen (MA)-specific CD8 + cell repertoire in PBMC of 40 healthy human donors (HD).

Tyr triggered interferon gamma (IFN-γ) secreting CD8 + T-cells in 25% of HD within 24h of antigen stimulation ex vivo. MAGE A3, Melan-A/MART-1, and gp100 also induced recall responses in 10%, 7.5%, and 2.5% of HD, respectively.

At this time point, these CD8 + T-cells did not yet produce GzB (granzyme B). However, they engaged in GzB production after 72 h of antigen stimulation.

By this 72h time point, 57.5% of the HD responded to at least one, and typically several, of the MA.

This article was originally published in the ‘Cancer Immunology, Immunotherapy’ journal.