Cutting Edge: Roles for Batf3-Dependent APCs in the Rejection of Minor Histocompatibility Antigen-Mismatched Grafts

Abstract

In transplantation, a major obstacle for graft acceptance in MHC-matched individuals is the mismatch of minor histocompatibility Ags. Minor histocompatibility Ags are peptides derived from polymorphic proteins that can be presented by APCs on MHC molecules. The APC subtype uniquely responsible for the rejection of minor Ag-mismatched grafts has not yet been identified. In this study, we examined graft rejection in three mouse models: 1) mismatch of male-specific minor Ags, 2) mismatch of minor Ags distinct from male-specific minor Ags, and 3) skin transplant. This study demonstrates that in the absence of pathogen-associated molecular patterns, Batf3-dependent dendritic cells elicit the rejection of cells and grafts expressing mismatched minor Ags. The implication of our findings in clinical transplantation may be significant, as minor Ag reactivity has been implicated in the pathogenesis of multiple allograft tissues.

FIGURE 1

Rejection of male-specific minor Ags requires Batf3-dependent DCs. (A) Gated CD8⁺ T cells display the recall of AT CD45.1 male Va2⁺ OT-I T cells (gray gate) in WT male and female mice. (B) For in vivo CTL assays, male OT-I cells were AT into WT male and female mice 1 d prior to intranasal administration of 2 μg OVA, which expands male Ag-specific T cells, and 10 d later mice were i.v. administered (1:1) CFSE-labeled male (CD45.2⁺)/female (CD45.1⁺) target cells. Three days after target cell AT, cytotoxicity was assessed. (C) Gated CD8 (upper panels) or CD4 (lower panels) T cells display the recall of AT CD45.1 male Va2⁺ T cells (gray gate, OT-I [upper panels] and OT-II [lower panels]) in BL/6 WT and Batf3^−/− male and female recipient mice. Scatter plots display frequency of OT-I and OT-II T cells from total CD8 and CD4 T cells. (D) Gated CD8 (upper panels) or CD4 (lower panels) T cells display the recall of AT CD45.1⁺KJ1-26⁺ or CD90.1⁺CD44⁺ male T cells (gray gate, CL4 [upper panels] and DO11.10 [lower panels]) from BALB/c WT and Batf3^−/− male and female recipient mice. Scatter plot displays frequency of CL4 and DO11.10 T cells from total CD8 and CD4 T cells. In (B)–(D), data are representative of three independent experiments. *p < 0.05.

FIGURE 2

Rejection of mismatched minor Ags requires Batf3-dependent DCs. Experimental design was as described in Fig. 1A. Gated CD8 T cells display the recall of CD45.1⁺Va2⁺ AT male (upper) and female (lower) OT-I T cells (gray gate) from 129SvEv/BL6 WT and Batf3^−/− male and female recipient mice. Scatter plots display frequency of OT-I T cells from total CD8 T cells. Data are representative of three independent experiments.

FIGURE 3

Rejection of male skin grafts on female recipients requires Batf3-dependent DCs. Representative images show transplanted murine skin grafts from BALB/c Batf3^−/− male and female donors onto BALB/c WT and Batf3^−/− female recipients (day 60). Survival graph displays male Batf3^−/− skin onto WT female (red diamond, 0 of 6) and Batf3^−/− female (blue circle, 6 of 6) recipients. For controls, survival graph displays female Batf3^−/− skin onto WT female (gray diamond, 5 of 6) and Batf3^−/− female (gray circle, 6 of 6) recipients. Data represent two independent experiments.

FIGURE 4

TLR7 ligand activates Batf3-independent DCs to promote rejection of mismatched minor Ags. Experimental design was as described in Fig. 1A. Plots display the recall of AT CD45.1 female C57BL/6 OT-I T cells (gray gate) from 129SvEv/BL6 WT and Batf3^−/− female mice immunized with sOVA ^+/− poly(I:C) (20 μg) or R848 (50 μg). Scatter plot displays frequency of OT-I T cells from total CD8 T cells. Data are representative of three independent experiments.