Allospecific CD154+ B cells associate with intestine allograft rejection in children.

Background: As a significant determinant of T- and B-cell cooperation, CD154 has been used to identify allospecific T-cytotoxic memory cells (TcM) for rejection risk assessment with high sensitivity or specificity but not for alloreactive B-cells, especially among recipients predisposed to acute cellular and humoral rejection, that is, children with intestinal transplantation (ITx).

Methods: Single blood samples from 32 pediatric ITx after lymphocyte depleting induction therapy were obtained within 30 days of protocol biopsies. Samples were assayed for allospecific CD154CD19 B cells and allospecific CD154 TcM in 16-hr live-cell mixed leukocyte reaction using multiparametric flow cytometry. Results were expressed as the immunoreactivity index (IR) or the ratio of donor- to third-party-induced CD154 B cells or TcM. The rejection threshold IR of B cells was determined by logistic regression, leave-one-out cross-validation, and receiver operating characteristic analyses.

Results: Biopsy-proven acute cellular rejection was present in 15 subjects (rejectors) and absent in 17 (nonrejectors). In archived serum samples from 16 of 32 subjects donor-specific anti-HLA antibodies (DSA) were assayed by Luminex bead array. DSA were absent in all 7 nonrejectors but present in 7 of 9 rejectors. The IR of allospecific CD154CD19 B cells more than or equal to 1.351 was associated with rejector status and was present in 13 of 15 rejectors (sensitivity 87%) and absent in 15 of 17 nonrejectors (specificity 88%). Excellent correlations were seen between CD154CD19 B cells and CD154 TcM (Spearman ρ=0.647, P=0.0001) but could not be tested independently for DSA, which was highly correlated with rejector status and with CD154 TcM.

Conclusions: Allospecific CD154CD19 B cells identify rejection-prone children with ITx and can likely substitute for T-cell alloreactivity in estimating rejection risk in this rare subject population.