The Umbilical Cord Blood αβ T-Cell Repertoire: Characteristics of a Polyclonal and Naive but Completely Formed Repertoire

Abstract

Umbilical cord blood (CB) constitutes a promising alternative to bone marrow for allogeneic transplantation and is increasingly used because of the reduced severity of graft-versus-host disease after CB transplantation. We have compared the T-cell receptor β chain (TCRB) diversity of CB lymphocytes with that of adult lymphocytes by analyzing the complementarity determining region 3 (CDR3) size heterogeneity. In marked contrast to adult samples, we observed bell-shaped profiles in all of the 22 functional β-chain variable (BV) subfamilies that reflect the lack of prior antigenic stimulation in CB samples. However, the mean CDR3 size and BV usage were comparable between CB and adult samples. BJ2 (65%) segments were used preferentially to BJ1 (35%), especially BJ2S7, BJ2S5, BJ2S3, and BJ2S1, in both CB and in adult lymphocytes. We therefore conclude that although naive as reflected by the heterogeneity of the CDR3 size, the TCRBV repertoire appears fully constituted at birth. The ability to expand TCRB subfamilies was confirmed by stimulation with staphylococcal superantigens toxic shock syndrome toxin-1 and staphylococcal enterotoxin A. This study provides the basis for future analysis of the T-cell repertoire reconstitution following umbilical CB transplantation.

The developing human immune system: T‐cell receptor repertoire of children and young adults shows a wide discrepancy in the frequency of persistent oligoclonal T‐cell expansions

“…28 Several studies have shown that cord blood TCR expression in cord blood T cells is highly diverse. 2,11 Previous reports of oligoclonal TCR expression in children have been in association either with HIV infections, 35 autoimmunity, 24 or immunode®ciency. 36 In this study we have shown that even healthy young children can have clonotypes that are signi®cantly expanded relative to the diverse repertoire, and that these expansions are persistent, and stable over time.…”

Umbilical Cord Blood Banking: Helping Parents Make Informed Choices

“…A diminished risk of acute graft-versus-host reaction provides another benefit (Rocha et al, 2001). This is because the cord-blood-derived lymphocytes, a type of white blood cells, are immunologically naïve, and the T-cells produce fewer cytokines and natural killer cells (Garderet et al, 1998). Thus, there is less potential for an immune response.…”

Basic mechanisms of humoral rejection

“…1). The human T cell repertoire achieves full diversity in utero (2), and the ability to mount a T-cell-dependent B-cell response is thought to be fully competent at birth (3). This level of immunocompetence contrasts with competence of the immune system in mice, which is clearly defective at birth (4).…”