Phytoderivates in rabbit diet and immune responses

In order to investigate the effects of some dietary phytoderivates (Origanum vulgare L. and Rosmarinus officinalis L.) on rabbit peripheral lymphocyte proliferation and subsets populations, a total of 100 New Zealand mixed-sex rabbits were weaned at 30 days of age and immediately split into homogeneous groups submitted to the following dietary treatments: 1) Standard diet (Ctrl); 2) Standard diet +150 ppm Vit E (Vit E); 3) Standard diet +0.2% oregano (O); 4) Standard diet +0.2% rosemary (R) and 5) Standard diet +0,1% oregano + 0.1% rosemary (OR). Blood samples were collected from rabbits at 30 days (Time 0, n.10 rabbits) and 90 days of age (Time 1; n.5 animals/diet group). A diet effect on lymphocyte proliferation test was observed in the “O” group, where its response to pokeweed mitogen (PWM) and interleukin-2 (IL-2) at Time 1 resulted significantly higher than that of the other experimental diet groups (PWM, P<0,001 and IL-2, P< 0,000), with the exception of “OR” group whose IL-2 mitogen response was as significant higher as that of “O” group. Furthermore, the basal mitogenesis values revealed higher responses at Time 1 in the “Vit E” and “O”, but the addition of mitogens induced significant increased responses only in the “O” group. No diet effects were registered on the lymphocyte subsets. The lymphocyte proliferation test in the control group showed a general reduction of leukocytes response with age, in particular it was observed a significant reduced response to PWM and PHA mitogens (P<0,021). Age effects were also recorded on lymphocyte subsets with a significant increase of CD8+ % with age (P<0,000). These results seem to encourage the integration of rabbit diet with oregano for its positive effect on adaptive immune response (a better in vitro reactivity of B cells).