In HLH, there is excessive activation of CD8+ T-Cells. Most commonly, this occurs due to Epstein-Barr virus infection.
CD8+ T-cells release IFN-γ that in turn activates macrophages. This disrupts the immune homeostasis and phagocytosis of all blood cells takes place.
The cross-talk between various cells of the immune system forms an auto-amplification loop. This cross-talk is by pro-inflammatory cytokines primarily TNF-alpha, IL-1, and IFN-gamma. IL-6 and IL-12 are also implicated.
Sporadic cases are associated with Chediak-Higashi syndrome. It can be acquired secondary to EBV infection or malignancy, usually lymphomas.
Fever is typically seen in hemophagocytic lymphohistiocytosis. This is due to massive interleukin-1 release, which raises the temperature setpoint of the hypothalamus.
Hepatosplenomegaly can occur from extramedullary hematopoiesis because the medullary space is undergoing increased hemophagocytosis.
Serum ferritin is an acute-phase reactant that is upregulated by TNF-alpha. It is characteristically elevated in patients with HLH.
Pancytopenia is defined as a decrease in the number of all cell lines in the blood i.e erythrocytes, leukocytes, and platelets. It is due to phagocytosis.
Immunosuppressants are used to control cytokine storm. Hematopoietic stem cell transplantation is potentially curative and is the only definitive treatment.
Picmonic's rapid review multiple-choice quiz allows you to assess your knowledge.
*Average video play time: 2-3 minutes
Unforgettable characters with concise but impactful videos (2-4 min each)