These ITP groups were compared with age-matched healthy controls to determine whether the observed differences were due to the disease itself or the effects of ageing.<h4>Methods</h4>Blood samples were processed and stained using the EuroFlow 8-colour PIDOT and pre-germinal centre B-cell tubes, following the EuroFlow SOPs for staining cell surface membrane markers.<h4>Results</h4>Patients with ITP>65, compared with those ≤65, showed reduced immature/transitional B cell subsets, an increased population of CD21-CD24- naïve B cells, and higher plasma B-cell activating factor levels. The gene discussed is TNFSF13B; the disease is autoimmune thrombocytopenic purpura.