CD8⁺ T-cell responses in persons with protective class I and II HLA alleles. (A) Total magnitude of the CD8⁺ T-cell responses in rectal mucosa in persons with or without protective class I and/or class II HLA alleles. Horizontal bars represent the median for each group. *P < .05, **P < .01. (B) Mucosal CD8⁺ T-cell polyfunctional responses broken down into 31 individual response categories. Each bar represents the median and interquartile ranges for the frequency of responding CD8⁺ cells in persons with or without protective class I and/or class II HLA alleles. Statistical differences between persons with both protective class I and class II alleles and other groups are marked by an asterisk (*) and color coded for each patient group (green indicates class II only; purple, no protective HLA). All differences were significant at P < .01.