Aim To understand whether peripheral blood monocytes from diet-induced hypercholesterolemic rabbits synthesize and secret increased growth factors and whether they release a high level of growth factors ,when stimulated with concanavalin A(Con A).Methods The male Japanese lop rabbits were fed on a diet containing 2% cholesterol to develop hypercholesterolemia(HC). The peripheral blood mononuclear leukocytes were isolated using a lymphocyte separation medium. After adhesion and washing to remove the non-adhered cells ,the monocytes were harvested and cultured in serum-free DME/F12 medium containing Con A or not.At different intervals the monocyte conditioned media(MC-CMs)under different conditions were collected. The mitogenic assays included:1)Incorporation of 3H-TdR into DNA in NIH 3T3 fibroblasts;(2)The effects of MC-CMs on the cell cycle were examined by flow cytometry; (3)Cell counting.Results The amount of 3H-TdR incorporation into DNA in NIH 3T3 cells induced by Con A-activated hypercholesterolemic rabbit (Con A-Act-HC-MC-CM )was 4.3 and 1.6 times that induced by non-activated hypercholesterolemic rabbit MC-CM(Non-Act-HC-MC-CM )and Con A-activated normal rabbit MC-CM(Con A-Act-N-MC-CM ),and the amount of 3H-TdRincorporation induced both by Non-Act-HC-MC-CM and Con A-Act-N-MC-CM was 1.3 and 3.4 times ,respectively, than that induced by non-activated normal rabbit MC-CM. Meanwhile the mitogenic activity of all the MC-CMs was significantly stronger than that of the unconditioned medium. Furthermore ,the cell number of S+G,M phases and the total cell number of the 3T3 cells cultured in Con A activated hypercholesterolemic and normal rabbit MC-CMs increased obviously.Conclusions The peripheral blood monocytes from the rabbits with hypercholesterolemia were in a active state, they could release a high level of growth factors,when stimulated(e.g.by Con A).