Results: The control group differed significantly from the leptospirosis and septic shock patients which demonstrate strong similarities: diffuse congestion in the red pulp with a moderate to intense infiltration of plasma cells and polymorphonuclear cells; follicles with marked atrophy; high density of CD20+ cells; low density of NK, TCD4+ and active caspase-3 positive cells and strong expression of IL-10; leptospirosis patients had higher S100 and TNF-α positive cells in the spleen than the other groups. The gene discussed is TNF; the disease is leptospirosis.