A: Human T cells (as indicated by CD3 surface marker) were evident in the peripheral blood of most recipient mice by 2 weeks after adoptive transfers, and typically increased over the next 2 weeks. *P = 0.04. Heavy horizontal line indicates mean. B: Human T cells comprised significant proportions of cells within spleens of recipient mice after adoptive transfer. There were no significant differences in the extent of splenic chimerism between recipient animals that received only adoptive transfers of peripheral blood mononuclear cells (PBMNC) (n = 15) and those that received concomitant PBMNCs and heterotopic airway grafts (HAG) (n = 14). C: The activation marker HLA class II DR was significantly up-regulated on chimeric T cells (n = 17), compared with expression on the original, donor lymphocytes (n = 6). There were no apparent differences in extent of chimeric T-cell activation between PBMNC only and PBMNC + HAG, so both groups were combined for this analysis. P values are indicated next to brackets. D: A large proportion of chimeric CD4 T cells did not coexpress CD28, but these cells more frequently produced granzyme B, relative to the original donor lymphocytes, which is analogous to findings in human lung allograft recipients with chronic allograft rejection.14P values are indicated next to brackets. In box plots (B–D), the lower whisker denotes the 10th percentile; the lower edge of the box, the 25th percentile; the middle line, the median; the square, the mean; the upper edge of box, the 75th percentile; and the upper whisker, 90th percentile.