Schematic representation of variation in immunogenicity detected in somatic cells after iPS generation and further differentiation.

<p>The red dots represent HLA-I expressed in somatic cells, their iPS cells and the iPS derivatives. Expression of HLA-I was decreased by the reprogramming event and increased during differentiation. Different somatic cells may have different immunogenicity (high or low), displaying as HLA-I expression. After reprogramming into iPS cells, the HLA-I expression reduces into a lower level regardless of cell origins. Different expression levels of HLA-I appear again when these iPS cells differentiate. iPS cells derived from less immunogenic somatic cells result in less immunogenic iPS derivatives, and vice versa. Blue cells represent more immunogenic cell types; green cells represent less immunogenic cell types.