CD4 and infection: We observed an increased memory T, in particular CD4+, lymphocyte immune infiltration within the lungs of COPD patients, compared with ever- and never-smoker controls, all of whom died of COVID-19, which was associated with an upregulation of crucial genes associated with SARS-CoV-2 entry and infection (e.g., ACE2, TMPRSS, and ORF1ab).