Age-related and disease-specific changes in B-cell profiles in older adults with immune thrombocytopenia

INTRODUCTION: Immune thrombocytopenia is an autoimmune bleeding disorder that is more prevalent among older adults. Ageing itself reduces B-cell counts, a change also observed in patients with ITP. This study examined the B cell profiles of patients with ITP aged over 65 (ITP>65) and aged 65 or under (ITP ≤ 65). 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. METHODS: 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. RESULTS: 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. Comparison of the ITP ≤ 65 group with the HC ≤ 65 group showed that patients with ITP had a lower B-cell count, but a significant increase in the CD21-CD24- naïve B-cell subset. Patients with ITP>65 had expanded CD21-CD24- and CD21-CD24++ naïve and memory IgMD+ B-cell populations compared to the HC>65 group. CONCLUSION: These findings suggest that ageing induces modifications to the B-cell phenotype that are similar to those observed in patients with ITP, except for the expansion of the CD21-CD24- naïve B-cell subset, which appears to be a characteristic of ITP shared with other autoimmune diseases.