Recognition of GPI-positive (normal) and GPI-negative (PNH) cells by allogeneic mHa-reactive T-cell lines. The mHa-specific CTLs were expanded from posttransplantation PBMCs of patient nos. 3 and 5. (A) The mHa-reactive CTLs expanded from patient no. 3 contained a mixture of CD4⁺ and CD8⁺ T cells. (B) These CTLs showed similar recognition of GPI-negative and GPI-positive monocytes (mono) as determined by an ELISA measuring IFN-γ secretion. (C) At multiple effector-target (E/T) ratios, a slightly higher percentage of GPI-negative (CD19⁺/CD55^–/CD59^–) compared with GPI-positive (CD19⁺/CD55⁺/CD59⁺) B cells were killed by these CTLs. (D) The mHa-reactive CTLs expanded from patient no. 5 contained predominantly CD8⁺ T cells. (E) Similar levels of cytotoxicity of GPI-negative and GPI-positive B cells were observed. Error bars represent 1 standard deviation.