CD4 T Cells Selected by Antigen Under Th2 Polarizing Conditions Favor an Elongated TCRα Chain Complementarity-Determining Region 3

Abstract

The affinity of the MHC/peptide/TCR interaction is thought to be one factor determining the differentiation of CD4+ T cells into Th1 or Th2 phenotypes. To study whether CD4+ cells generated under conditions favoring Th1 or Th2 responses select structurally different TCRs, Th1 and Th2 clones and lines were generated from nonobese diabetic and nonobese diabetic H2-E transgenic mice against the peptides proteolipoprotein 56–70, glutamic acid decarboxylase65 524–543, and heat shock protein-60 peptides 168–186 and 248–264. Th1/Th2 polarization allowed the generation of clones and lines with fixed peptide specificity and class II restriction but differing in Th1/Th2 phenotype in which the impact on TCR selection and structure could be studied. The Th2 clones tended to use longer TCR complementarity-determining region (CDR)3α loops than their Th1 counterparts. This trend was confirmed by analyzing TCRα transcripts from Th1 and Th2 polarized, bulk populations. Molecular modeling of Th1- and Th2-derived TCRs demonstrated that Th2 CDR3α comprised larger side chain residues than Th1 TCRs. The elongated, bulky Th2 CDR3α loops may be accommodated at the expense of less optimal interactions between the MHC class II/peptide and other CDR loops of the TCR. We propose that CD4+ T cells selected from the available repertoire under Th2 polarizing conditions tend to have elongated TCR CDR3α loops predicted to alter TCR binding, reducing contact at other interfaces and potentially leading to impeded TCR triggering.

CTLA-4 controls the thymic development of both conventional and regulatory T cells through modulation of the TCR repertoire

“…CTLA-4WT and CTLA-4KO Tconv cells differed in CDR3α length; in both, ∼2/3rds of sequences were 20 aa in length, whereas the remaining 1/3rd was either 19 or 18 aa in length, respectively. The length of the CDR3 region has previously been implicated in the differentiation of Tconv cells to either a Th1 or Th2 phenotype (53). Similarly, CTLA-4-deficient mice have been shown to exhibit a skewed repertoire of Th1, Th2, and Th17 cells, which was also reported here for Tg4 CTLA-4KO mice (28,(35)(36)(37)).…”

Recent thymic emigrants are biased against the T-helper type 1 and toward the T-helper type 2 effector lineage

“…The Th2 bias may be influenced by repertoire shaping, given that the TCR-␤ chains expressed by CD4 ϩ RTEs are skewed toward longer CDR3 regions than those of MN T cells. 26 In line with these data, Boyton and colleagues 27 have shown that relative to Th1 clones, Th2 clones have significantly longer TCR-␣ CDR3 loops. The Th2 bias may also be influenced by differences in TCR signaling between RTEs and MN T cells.…”

Nuclear repositioning marks the selective exclusion of lineage‐inappropriate transcription factor loci during T helper cell differentiation

“…2c illustrates measurements for individual GATA-3 alleles normalized to the nuclear radius, confirming the preferential association of GATA-3 with centromeric heterochromatin in polarized Th1 but not Th2 cells (p<0.01). This preferential association persisted in long term T cell lines and clones (p<0.01, Th1 clone D5 [23] versus Th2 clone D10 [24] and Th2 line GAD [25]). The cytogenetic position of the GATA-3 locus only 9.8 Mb from the centromere of chromosome 2 (Ensemble) is likely to impose topological restrictions, underlining the significance of the differential positioning of GATA-3 in Th1 and Th2 interphase nuclei [26].…”

“…T cell clones D5 (Ar-5) [23] and D10 (D10.G4.1) [24] were cultured in Dulbecco's modified Eagle's medium supplemented with 10% FCS, L-glutamine, penicillin-streptomycin, nonessential amino acids, sodium pyruvate, vitamins, HEPES, and 2-ME and 20 U/ml human rIL-2 (for D5) or 25 U/ml recombinant IL-4 (for D10). PGL2 (Th1) and PL104 (Th2) clones and the Th2 anti-GAD 524-543 T cell line have been described [25,42].…”