T follicular helper (Tfh) cell migration into germinal centers (GCs) is essential for the generation of GC B cells and antibody responses to T cell–dependent (TD) antigens. This process requires interactions between lymphocyte function–associated antigen 1 (LFA-1) on Tfh cells and ICAMs on B cells. The mechanisms underlying defective antibody responses to TD antigens in DOCK8 deficiency are incompletely understood. We show that mice selectively lacking DOCK8 in T cells had impaired IgG antibody responses to TD antigens, decreased GC size, and reduced numbers of GC B cells. However, they developed normal numbers of Tfh cells with intact capacity for driving B cell differentiation into a GC phenotype in vitro. Notably, migration of DOCK8-deficient T cells into GCs was defective. Following T cell receptor (TCR)/CD3 ligation, DOCK8-deficient T cells had impaired LFA-1 activation and reduced binding to ICAM-1. Our results therefore indicate that DOCK8 is important for LFA-1–dependent positioning of Tfh cells in GCs, and thereby the generation of GC B cells and IgG antibody responses to TD antigen.
Erin Janssen, Mira Tohme, Jordan Butts, Sophie Giguere, Peter T. Sage, Francisco E. Velázquez, Christy Kam, Elena Milin, Mrinmoy Das, Ali Sobh, Salem Al-Tamemi, Francis W. Luscinskas, Facundo Batista, Raif S. Geha