Fig. 7: Immune infiltration into human retinoblastoma occurs primarily in tumors with significantly reduced Ki67 proliferative index.

Human retinoblastoma samples display a significant inverse relationship between proliferation and immune cell infiltration. A Fourteen human retinoblastoma samples on a tissue microarray were stained simultaneously by immunohistochemistry for the proliferation marker Ki67 or for CD45, the “leukocyte common antigen” to detect immune cells. Five representative samples are shown: two have high Ki67 and low CD45⁺ cells, and two show the reverse phenotype. B Each sample was scored based on the number of Ki67 and CD45 positive cells. Tumors with greater than 50% Ki67⁺ cells were marked “high” and those with less than 50% as “low”. Tumors with greater than 5% immune cells were marked high, and less than 5% low. Scores for Ki67 and CD45 were compared against each other and found significant using Fisher’s exact test (p < 0.01).