• Macrophage activation syndrome along with hyperactivation of monocytes was found in severe cases.• Decrease in lymphocyte number (CD4+T and B cells) along with decline in NK cells was observed.• Blood IL-6 and CRP levels were increased in severe cases. Further, increased levels of fibrinogen, D-dimers, creatinine was found in severe cases. This evidence concerns the gene IL6 and macrophage activation syndrome.