Monocyte profiles of patients with long COVID with fatigue. Summary graphs showing data from healthy individuals and all convalescent COVID-19 patients. a) Frequencies of CD14+ monocytes expressing COX-2 from healthy individuals (n=32) and all convalescent COVID-19 (Conv C-19) patients (n=121). Patients with convalescent COVID-19 were also stratified into asymptomatic (no breathlessness or fatigue: n=45), breathless only (breathless but not fatigued: n=15) or fatigue only (fatigued but not breathless: n=22) and into mild (n=26), moderate (n=44) or severe (n=52) disease, referring to acute COVID-19 severity during previous hospital admission (for all convalescent patients). b) Correlation of COX-2 (percentage of monocytes expressing COX-2) with number of days since hospital discharge, in all convalescent COVID-19 patients (n=122). c) Frequencies of CD14+ monocytes expressing CXCR2 from healthy individuals (n=34) and all convalescent COVID-19 patients (n=133). Patients with convalescent COVID-19 were also stratified into asymptomatic (n=51), breathless only (n=18) or fatigue only (n=25) and into mild (n=30), moderate (n=44) or severe (n=59) disease, referring to acute COVID-19 severity during previous hospital admission (for all convalescent patients). d) Correlation of CXCR2 (percentage of monocytes expressing CXCR2) with number of days since hospital discharge in all convalescent COVID-19 patients (n=128). e) Frequency of CD14+ monocytes producing TNF-α in healthy individuals (n=33) and convalescent COVID-19 patients stratified into asymptomatic (n=45), breathless only (n=15) or fatigue only (n=23). f) Frequency of CD14+ monocytes producing IL-1β in healthy individuals (n=34) and convalescent COVID-19 patients stratified into asymptomatic (n=45), breathless only (n=15) or fatigue only (n=23). g) Frequency of CD14+ monocytes expressing CXCR6 in healthy individuals (n=35) and convalescent COVID-19 patients stratified into asymptomatic (n=45), breathless only (n=19) or fatigue only (n=22). h) CD14+ monocyte levels of expression of PSGL-1 as determined by mean fluorescence intensity (MFI) in healthy individuals (n=35) and convalescent COVID-19 patients stratified into asymptomatic (n=50), breathless only (n=18) or fatigue only (n=24). All graphs show individual patient data with bars representing mean±sem. Comparison of groups was carried out using unpaired t-test (a, c: healthy versus convalescent COVID-19), one-way ANOVA with Holm–Sidak post hoc test (a, c, e-h: long COVID symptoms, original severity) or Pearson correlation coefficient test (b, d). *: p≤0.05; **: p≤0.01; ***: p≤0.001; ****: p≤0.0001.