ANXA1 and systemic lupus erythematosus: The IgG2 isotype of anti-Annexin A1 antibodies in SLE/lupus nephritits is in agreement with the concept that SLE and lupus nephritis are two autoimmune conditions characterized by isotype specificity of auto-antibodies [35,40] and differ from other autoimmune conditions that are instead characterized by IgG4 isotype specificity (such as in the case of membranous nephropathy) [71,72] or by IgG3 specificity (such as in the case of autoimmunity associated with infections and cancer) [73].