Effects of silk lutein extract and marigold lutein extract on in vitro lymphocyte proliferation. Splenic cells were isolated from BALB/c mice fed lutein extracts from silk cocoons or marigolds daily for 4 weeks and cultured in the presence of ConA (A) or LPS (B) at 37°C in a 5% CO2 incubator. After 20 hours, MTT assay was performed. Values represent means ± SEM. * P < 0.05; ** P < 0.01 compared to the control. SLT10, SLT20; silk lutein extract 10 and 20 mg/kg groups, CLT10, CLT20; marigold lutein extract 10 and 20 mg/kg groups.