Venom promotes germinal center formation. BALB/c mice were immunized i.p. with 10 μg of T. nattereri venom adsorbed in Al(OH)3 on day 0 and boosted on day 14 with the same dose of venom. Animals injected only with Al(OH)3 were considered as control group. After 120 days of immunization is observed typical B cell areas in lymphoid follicles of spleen showing an increased expansion of germinal centers compared with than control-mice.