N-Terminally LRMK-linked HER-2 peptides, AE-37 (p776(774-788)) and AE-47 (Ava-F7(776-788)), Aid Differentiation of E75-TCR+ CD8 + Cells to Perforin-positive Cells

The objective of this study was to discover whether the peptides LRMK and LRMK-Ava linked to the N-terminus of peptides HER-2 (774-788) and HER-2 (776-788), respectively, help differentiation of E75-TCR+CD8+ cells. Activation was quantified in terms of proliferation of E75-TCR+CD8+ cells expressing high, medium and low density amounts of the specific TCR. Differentiation to functional CD8+ cells was quantified as induction of Perforin (Perf), the lytic-enzyme which mediates the effector function of CD8+ cells, in E75-TCR+CD8+ cells. Peripheral blood mononuclear cells (PBMCs) of 3 patients activated with E75+AE-37 and E75+AE-47 more greatly increased the number of E75-TCRHi CD8+Perf+ cells than PBMCs activated by AE-47 alone or AE-47+ E75. E75 plus cytokines and cytokines alone activated more E75-TCRLow cells than did AE-37 and AE-47. E75+ AE-37 and AE-37 also induced differentiation of small- and medium-size activated CD8+ cells from BRC ascites, in allogeneic activation, to Perf+ cells. Preferential differentiation of E75-TCR+CD8+Perf+ cells in distinct patients by AE-37 and AE-47 indicates that cancer vaccines will benefit from such correct individual and disease-associated help. Additional studies using the natural peptides p776 and F7 are needed to understand whether the LRMK-(Ava) tetra-, or pentamer augments or inhibits differentiation of CD8+ cells, compared with native, natural HER-2 peptides and/or protects CD8+ cells activated by E75 and by other HLA-I bound peptides from death. Our findings also develop a model for uniform quantification of differentiated CD8+ effectors.