Effects of Oregano (Origanum vulgare L.) and Rosemary (Rosmarinus officinalis L.) Aqueous Extracts On in vitro Rabbit Immune Responses

In order to investigate the effects of some dietary phytoderivates (Origanum vulgare L. and Rosmarinus officinalis L.) on rabbit immune system, 100 New Zealand mixed-sex rabbits weaned at 30 days of age were split into homogeneous groups submitted to the following dietary treatments: 1) Standard diet (C); 2) C +150 ppm Vit E (E); 3) C +0.2% oregano (O); 4) C +0.2% rosemary (R) and 5) C +0.1% oregano + 0.1% rosemary (OR). Blood samples were drawn from rabbits at 30 and 90 days of age (ten rabbits/diet group at Time 0 and 1, respectively) to investigate the blood lymphocyte subset evolution, the in vitro lymphocyte proliferation (in presence or absence of mitogens) responses and the Immunoglobulin M (IgM) concentration in the supernatants of lymphocyte cultures. A diet effect was observed in the O and OR groups, where the lymphocytes proliferation responses to pokeweed mitogen (PWM; ***P<0.001, in the O group) or the interleukin-2 production (IL-2; ***P<0.001, for both groups) at Time 1 were significantly higher. The IgM levels were systematically higher in the O, OR and E cells culture supernatants (**P<0.01). Age did not affect the rabbit lymphocyte subset evolution nor the in vitro lymphocyte proliferation. Data obtained in the present study show that rabbit’s dietary supplementation with oregano elicits positive effects on the adaptive immune response.