Fessler J, Fasching P, Raicht A, et al. - By performing this prospective, cross-sectional analysis of consecutive patients with primary Sjögren’s syndrome (pSS) (n = 66) and healthy controls (n = 181), researchers investigated peripheral lymphopenia, a common revelation in pSS related to higher disease activity and increased mortality. Via flow cytometry, lymphocyte subsets were examined, and using MACS technology, naïve (CD45RA⁺) and memory (CD45RO⁺) CD4⁺ T cells were purified. Naïve CD4⁺ T cells were predominantly influenced by lymphopenia in pSS. Experts identified a lower frequency of proliferating naïve CD4⁺ T cells ex vivo, and they also noted reduced homeostatic proliferation in response to IL-7 stimulation in vitro. Signs of immune cell aging were shown by naïve CD4⁺ T cells, including shortened telomeres, a decrease in IL-7R expression and accumulation of senescence-associated β-galactosidase. According to the findings, evidence for increased proliferation of naïve CD4⁺ T cells earlier in life, in pSS, was found to be related to a senescent phenotype unable to sustain homeostasis. The basis of lymphopenia often noted in pSS is formed by the lack of naïve CD4⁺ T cells.