Transfer of donor pathogen-specific clones across the HLA barrier. X axes: weeks after transplantation and number of evaluable patients at each time point. (A-D) Frequencies of Aspergillus- and CMV-specific T cells were monitored by limiting dilution analyses of proliferating pathogen-specific T cells for 36 weeks after transplantation (“Patients, materials, and methods”). As all clones exhibited the CD3⁺/CD4⁺ phenotype, frequency results obtained by limiting dilution analyses are expressed as the number of CD3⁺/CD4⁺ growing clonal cultures in 10⁶ plated CD3⁺/CD4⁺ cells. (A,C) Frequencies of CD4⁺ T-cell clones specific for Aspergillus (A) and for CMV (C) in haploidentical transplant recipients who did not receive adoptive therapy (13 and 33 patients, respectively). (B,D) Frequencies of CD4⁺ T-cell clones specific for Aspergillus (B) and for CMV (D) in haploidentical transplant recipients who received adoptive therapy (10 and 25 patients, respectively). Box and whisker plots indicate mean, SD, and range of frequencies. Frequencies of Aspergillus- and CMV-specific CD4⁺ T-cell clones in infused patients versus controls: P < .005 at all time points. (E-F) Frequencies of CMV-specific CD8⁺ T cells as detected by ELISPOT in noninfused patients (E) and in infused patients (F) for 24 weeks after transplantation. Box and whisker plots indicate mean, SD, and range of frequencies. Frequencies of CMV-specific CD8⁺ T cells in infused patients versus controls: P < .005 at all time points.