Figure 6

Susceptibility of porcine target cells to cell death induced by human cytotoxic effector cells. A total of 1 × 10⁵ porcine target cells (L23-control and L23-E3/49K) were co-cultured with 1 × 10⁵ human cytotoxic effector cells. After 2 h the cells were washed and stained with a combination of monoclonal antibody W6/32 (anti-human HLA class-I) and Annexin V. Analysis of Annexin V staining was performed in “gated” porcine L23 cells as defined by absence of W6/32 staining. (A) Representative histograms of Annexin V staining in L23-control and L23-E3/49K cells alone (dashed lines) or after co-cultures with human anti-L23 sensitized T cell lines (CD8⁺ or CD4⁺), CD56⁺ NK and NKT cells or porcine CTL generated in vitro by allogeneic mixed lymphocyte reaction (pTeff) (solid lines). The dotted line discriminates viable (Annexin V^low) and apoptotic (Annexin V^high) cells. Numbers represent the proportion of apoptotic/dead L23 cells. (B) The bar graph summarizes percentages of apoptotic cells from 5 different experiments using cells from 2 blood donors (CD8⁺), 12 experiments with cells from 2 donors (CD4⁺), 4 experiments using cells from 3 different blood donors (CD56⁺), and 5 experiments with cells from 2 donors (pTeff). Statistical analysis was performed by applying the paired Student’s t-test.