Impairment of the T cell memory response in chronic lymphocytic leukemia patients after SARS-CoV-2 vaccination.

CLL patients face increased vulnerability to COVID-19 because of weakened immune systems from comorbidities and treatments. Therefore, the need for these patients of vaccination is of outermost importance. In our study we have evaluated T cell-mediated responses to COVID19 vaccines by performing the activation-induced markers (AIM) assay which allows to determine spike-specific CD4+ and CD8+ T cell responses. A CD4+ T cell memory response was registered in all healthy control (HC) (responders), while 28.60 % of CLL patients did not respond to the stimulation (non-responders). CD8+ T cell memory response was impaired in 61.90 % of CLL patients and in 33.33 % of HC. In addition, CLL responders showed a significant impairment of the magnitude of memory response in CD8 subset. Interestingly, impairment of the CD4+ AIM+ memory was associated to a more severe COVID-19 infection. Ibrutinib therapy had negative impact on IL-2 production by CD8+ cells, while the duration of the treatment positively affected the memory response. The majority of CLL patients don't respond well to vaccination, leaving clinicians in need of a reliable way to identify non-responders and assess the protection levels of those who do. Our findings suggest the AIM test as a promising method for screening and categorizing patients, potentially addressing this need.