IFNγ can be produced by innate (NK, NKT, antigen-presenting cells, neutrophils) and adaptive (CD4+, CD8+, B) immune cells [50,51] and is often elevated in patients with autoimmune diseases [50,52,53] and infections with respiratory viruses such as SARS-CoV-2 [54,55,56,57,58]. Here, CD4 is linked to autoimmune disease.