Fig. 1
From: T-ing up the storm: pathogenic cycling lymphocytes in the biology of macrophage activation syndrome
Schematic illustrating the causes of HLH / MAS and the role of various immune cell subsets in driving the cytokine storm. Infections, malignancies, medications, genetic defects in cytolysis, and inflammatory diseases are known triggers of HLH / MAS that lead to immune hyperactivation and cytokine storm. Critical immune cells include lymphocytes, macrophages, and antigen-presenting cells interact to drive the activation and expansion of pathogenic lymphocytes that produce IFN-γ. IFN-γ activates macrophages to produce other cytokines and chemokines to amplify the inflammatory cascade. *SH2D1A and XIAP/BIRC4 are associated with primary HLH but these genes are not directly involved in the cytolytic pathway