Ruscitti P, et al. - This study analyzed the presence of heavy (H)-ferritin and light (L)-ferritin; CD68+/H-ferritin+ and CD68+/L-ferritin+; and IL-1β, TNF, IFN-γ in bone marrow (BM) biopsies of adult patients with macrophage activation syndrome (MAS) and investigated possible correlations of these results with clinical data. Findings showed markedly elevated levels of H-ferritin, CD68+/H-ferritin+ cells and pro-inflammatory cytokines in the BM inflammatory infiltrate during MAS, indicating a possible vicious pathogenic loop. Furthermore, data suggested a significant association of H-ferritin and CD68+/H-ferritin+ with haematological involvement of the disease, indicating bio-markers assessing severity of clinical picture.