CD4 and laryngotracheoesophageal cleft: While the underlying causative mechanisms of LC remain to be defined, an accepted causative factor in a large subset of patients with LC, is that reservoirs of virus, viral RNA (vRNA), and/or fragments may persist and replicate in multiple sites of the body driving chronic inflammation, overstimulate innate and adaptive immune cells, and provide continuous viral antigenic stimuli to exhausted CD4+ and CD8+ T cells [31,33,34,35,36].