CCL21 and disease arising from reactivation of latent virus: In contrast to CD2 signaling, prestimulation of resting CD4 T cells with anti-CXCR4 antibody, with the chemokines CCL19/CCL21, or with IP-10 (CXCL10) has been shown to promote HIV-1 latent infection of resting CD4 T cells (Cameron et al., 2010; Saleh et al., 2007; Wang et al., 2021).