The effect of IL‐2 itself depending on the concentration of the cytokine, antigenic stimulation, the presence of other cytokines, target immune cells and other factors present in the microenvironment can vary from immunoregulatory (low concentrations in the above‐mentioned SLE patients), immunostimulatory effect of higher concentrations in anti‐infective or antitumor responses to the harmful effect of extremely high concentrations produced under the influence of bacterial superantigens in toxic shock syndrome. Here, IL2 is linked to systemic lupus erythematosus.