Therapeutic Modulation of T Follicular Helper Cells by Low-Dose IL-2 Treatment

T follicular helper (Tfh) cells are a subset of specialized CD4⁺ T cell residing in B cell follicles and confer essential support for germinal center responses, which lead to the generation of long-lived humoral immunity. A great deal of evidence from the past 15 years indicate that excessive differentiation and dysregulated function of Tfh cells often promote autoimmunity by inducing autoantibody production. Interleukin-2 was identified as a major suppressor to inhibit Tfh differentiation. Therefore, IL-2 treatment was applied in suppressing Tfh function in mouse models and more recently in a clinical trial of patients with systemic lupus erythematosus. Here we describe a protocol for low-dose IL-2 treatment in a murine immunization model and on the assessment of the suppression of Tfh response using flow cytometry.