Background. B-cell infiltrates are common in rejected kidney allografts, yet their composition is still unclear. The aim of our study was to characterize the clonal composition of B-cell infiltrates of rejected human kidney grafts.
Methods. We used a molecular approach to characterize the partial B-cell repertoires of 5 failed human kidney grafts with detectable B-cell infiltrates. A comparison between the intragraft and blood repertoire was also conducted for 1 case.
Results. Redundant sequences were observed in both blood and graft, although the level of clonal amplification was significantly higher for the graft. Somatic hypermutations (SHMs) were also more frequent in sequences found in the graft compared to the blood. The rate of nonsilent mutations was significantly higher in complementarity determining regions (CDRs) compared to framework regions in blood sequences as well as in graft sequences found at low frequency. In contrast, this preferential distribution was lost in sequences found at high frequency in the graft, suggesting a lack of affinity maturation in situ. Lastly, follicular dendritic cells were undetectable in CD20(+) infiltrates in all samples examined.
Conclusions. We provide here evidence that B-cell clones expand and undergo SHMs in situ. However, the even distribution of nonsilent SHM in high-frequency graft sequences together with the absence of follicular dendritic cells do not support the view that infiltrating B cells are part of functional germinal centers.
[1]Harvard Univ, Sch Med, Dept Surg, Transplant Ctr,Massachusetts Gen Hosp, Boston, MA 02115 USA.
[2]Jilin Univ, Hosp 1, Transplant Ctr, Changchun 130023, Peoples R China.
[3]Harvard Univ, Sch Med, Dept Pathol, Massachusetts Gen Hosp, Boston, MA 02115 USA.
[4]Harvard Univ, Brigham & Womens Hosp, Sch Med, Div Transplant Surg, Boston, MA 02115 USA.
[5]Harvard Univ, Sch Med, Dept Med, Renal Unit,Massachusetts Gen Hosp, Boston, MA USA.
(8.0+极速模式)