Haematological and immunological effects of repeated dose exposure of rats to integerrimine N-oxide from Senecio brasiliensis

► Integerrimine N-oxide (INO) is a pyrrolizidinic alkaloid found in Senecio spp. ► This study showed that INO induces immune and haematological changes in rats. ► Blood cell counts of rats treated with INO were altered. ► INO induces G1 cell cycle arrest with reduction of cells in the S phase. ► INO produces a reducing T cell proliferative activity.