Levels of anti-sheep erythrocyte antibodies in BALB/c mice fed silk lutein extract or marigold lutein extract. A day after cessation of treatment, mice were intraperitoneally injected with sheep erythrocytes as antigens. Second immunization was carried out on day 14 and blood samples were collected 7 days after the boost. Specific anti-sheep erythrocytes antibodies were determined by hemagglutination. Values represent means ± SEM. ** P < 0.01 compared to the control. SLT10, SLT20; silk lutein extract 10 and 20 mg/kg groups, CLT 10, CLT 20; marigold lutein extract 10 and 20 mg/kg groups.