Effects of Nigella sativa extracts on antibody response of rats vaccinated with brucella vaccine (Rev-1)

Abstract

Volatile oil (VO), polysaccharide (PS) and ethanol extracts (EE) of N. sativa were evaluated for their effects on the antibody (Ab) titer of rats vaccinated with Brucella melitensis vaccine (Rev-1). Thirty rats were divided into five equal groups. Group 1 (control) animals were injected with PBS, group 2 with Rev-1 alone, group 3 with Rev-1 and VO, group 4 with Rev-1 and PS and group 5 with Rev-1 and EE. The Ab titer was measured by Rose Bengal (RB) test, complement fixation (CF) test and tube agglutination (TA) test. All of the tests were negative in group 1. RB test occurred significantly faster in groups 4 and 5 than group 2 (P < 0.05 and 0.01, respectively). When the mean values of Ab titers of CF and TA in the groups was compared, significant differences (P < 0.05 or 0.01) were found between each of 2 and 3, 4, 5 and also between groups 3 and 4. When the percentages of lymphocytes and neutrophils were compared between the groups, significant differences were found between groups 1 and 3, and between 3 and 5. Histopathological examination of lymph nodes revealed a remarkably consistent picture of reactive lymphoid hyperplasia with prominence of germinal centers being evident in group 5. Infiltration of the medullary sinuses with plasma cells, lymphocytes, and macrophages was also seen. Our results suggest that all fractions of N. sativa had a significant adjuvant effect on the response of melitensis vaccine, and that PS was the most effective fraction.