IL-4 and IL-13: Together but Not Interchangeable

Overlapping biology is not the same as redundant biology. Jason Hawkes, MD, takes on a question that often trips up clinicians: is blocking IL-4 and IL-13 together the same as blocking IL-13 alone? He explains IL-4’s unique role in differentiating naive T cells into Th2 cells, along with its contributions to receptor expression and class switching to IgE and other autoantibodies, functions that help explain its relevance in chronic spontaneous urticaria and bullous pemphigoid. The distinction, he notes, is not that one cytokine is better, but that IL-4 can do what IL-13 does, while IL-13 cannot do everything IL-4 does.