Developmental control of CD8+ T cell–avidity maturation in autoimmune diabetes
Bingye Han, Pau Serra, Jun Yamanouchi, Abdelaziz Amrani, John F. Elliott, Peter Dickie, Teresa P. DiLorenzo, Pere Santamaria
Bingye Han, Pau Serra, Jun Yamanouchi, Abdelaziz Amrani, John F. Elliott, Peter Dickie, Teresa P. DiLorenzo, Pere Santamaria
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Research Article Autoimmunity

Developmental control of CD8+ T cell–avidity maturation in autoimmune diabetes

Abstract

The progression of immune responses is generally associated with an increase in the overall avidity of antigen-specific T cell populations for peptide-MHC. This is thought to result from preferential expansion of high-avidity clonotypes at the expense of their low-avidity counterparts. Since T cell antigen-receptor genes do not mutate, it is puzzling that high-avidity clonotypes do not predominate from the outset. Here we provide a developmental basis for this phenomenon in the context of autoimmunity. We have carried out comprehensive studies of the diabetogenic CD8+ T cell population that targets residues 206–214 of the β cell antigen islet-specific glucose-6-phosphatase catalytic subunit–related protein (IGRP206–214) and undergoes avidity maturation as disease progresses. We find that the succession of IGRP206–214–specific clonotypes with increasing avidities during the progression of islet inflammation to overt diabetes in nonobese diabetic mice is fueled by autoimmune inflammation but opposed by systemic tolerance. As expected, naive high-avidity IGRP206–214–specific T cells respond more efficiently to antigen and are significantly more diabetogenic than their intermediate- or low-avidity counterparts. However, central and peripheral tolerance selectively limit the contribution of these high-avidity T cells to the earliest stages of disease without abrogating their ability to progressively accumulate in inflamed islets and kill β cells. These results illustrate the way in which incomplete deletion of autoreactive T cell populations of relatively high avidity can contribute to the development of pathogenic autoimmunity in the periphery.

Authors

Bingye Han, Pau Serra, Jun Yamanouchi, Abdelaziz Amrani, John F. Elliott, Peter Dickie, Teresa P. DiLorenzo, Pere Santamaria

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Striking differences in the developmental biology of 17.4α/8.3β and 17.5...
Striking differences in the developmental biology of 17.4α/8.3β and 17.5α/8.3β T cells in Tg mice. Flow cytometry of thymocytes (A–D) and splenocytes (E–H). (A and E) Representative CD4 versus CD8 dot plots. P values for percentage of thymic and splenic CD8+CD4– cells were as follows: P < 0.017 (for 17.4α/8.3β Tg vs. 17.5α/8.3β Tg, 5- to 9-week-old mice). (B–D and F–H) Comparison of mfi with which the different T cell subsets stain with anti–TCR-Vβ8 or anti–TCR-β mAbs or with IGRP206–214 tetramers. Values on the panels correspond to percentage of cells contained within each quadrant (A and E) or to percentage of cells within each gate that stained (B–D and F–H) (mean ± SE). **P < 0.05 versus 17.4α/8.3β Tg mice. Representative histograms are shown. A–D and E–H are representative of 4–5 mice per strain per age group. Note that the representative dot plots and histograms corresponding to 17.4α/8.3β Tg mice are the same as those shown in Figure 2. The data are rendered twice to facilitate comparisons with results obtained with Tg mice bearing lower- (Figure 2) or higher-avidity T cells (this figure).