Abatacept is effective in Chinese patients with LRBA and CTLA4 deficiency

CTLA4 deficiency and LRBA deficiency are a group disorders of immune dysregula-tion that affect CTLA4 pathway.The patients mainly present with autoimmunity,antibody defi-ciency and recurrent infections.Here we reported three Chinese patients with LRBA and CTLA4 mutations.They all presented with chronic diarrhea,hypokalemia,organomegaly,recurrent in-fections,and hypogammaglobulinemia.Reduced Treg cells and increased percentage of circu-lating follicular helper T(cTfh)cells were revealed in these patients.Although steroid and immunoglobulin therapy were given,the enteropathy was persistent.Therefore,abatacept treatment was provided to these patients.They showed a marked improvement of enteropathy and gastrointestinal endoscopy showed alleviated inflammatory lesion and follicular hyperpla-sia.Furthermore,the frequency of cTfh cells was reduced after abatacept therapy.Taken together,targeted therapy with abatacept is a promising treatment modality for patients with LRBA and CTLA4 deficiency.The findings also suggest that the frequency of cTfh cells could serve as a marker for tracking disease activity and the response to abatacept therapy.