In situ detection of autoreactive CD4 T cells in the mouse models of autoimmune diseases (P4550)

Abstract

Abstract We report here the utility of major histocompatibility complex (MHC) class II dextramers for detecting self-reactive CD4 T cells in the target tissues using two mouse models of autoimmunity namely, experimental autoimmune encephalomyelitis and experimental autoimmune myocarditis. We determined the conditions for dextramer staining using brain sections obtained from SJL mice immunized with proteolipid protein (PLP) 139-151 by staining the sections with a cocktail of IAs/PLP 139-151 (specific) or Theiler’s murine encephalomyelitis virus (TMEV) 70-86 (control) dextramers conjugated with the fluorescent dyes, and CD4 antibody. The sections were examined by Olympus Fluoview laser scanning microscope, and the analysis revealed PLP 139-151 dextramer-positive cells to be colocalized to CD4-expressing cells, but such reactivity was lacking with TMEV dextramers, suggesting that the staining obtained with PLP dextramers was specific. We next extended these observations to detect cardiac myosin-specific T cells by deriving IAk dextramers for cardiac myosin heavy chain-α (Myhc) 334-352 and ribonuclease 43-56 (control). Expectedly, heart sections prepared from A/J mice immunized with Myhc 334-352 on day 21 postimmunization showed infiltrations of Myhc-specific CD4 T cells. The data suggest that MHC class II dextramers can be potentially used to enumerate the precursor frequencies of antigen-specific CD4 T cells in situ directly, without having to amplify the fluorescent signals.