IL10 and systemic lupus erythematosus: Immature B cells in SLE patients do not respond properly to known signals for Breg cell differentiation: while healthy immature B cells differentiate into Breg cells upon CD40 stimulation, CD24hiCD38hi B cells isolated from SLE patients do not produce IL-10 following CD40 activation and are unable to suppress Th1 responses (156, 193).