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

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).

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.

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.

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.