Abstract
Immunity is a major concept in human nutrition. Immunocompromised individuals are at risk for serious infection as COVID-19 which is directed the researchers to use the immunomodulatory plants for prophylaxis. This study was designed to assess the immune response of Wistar rats administrated Achillea fragrantissima (A. fragrantissima) extract versus Endoxan (immunosuppressive) and Echinaid (immune stimulating). Fifty rats were assigned into 5 groups: (1) control, (2) injected intraperitoneal (i/p) with Endoxan 90 mg/kg for three successive days, (3) injected with Endoxan as (2) and administrated with Echinaid 300 mg/kg/day. (4,5) injected with Endoxan as (2) and administrated with 300 and 500 mg/kg/day A. fragrantissima extract respectively. On day 17 all groups were challenged with two doses of sheep erythrocytes (SRBC) i/p, 2 weeks intervals. A high dose of A. fragrantissima extract achieved an increase in total antioxidant capacity significantly(P<0.05), superoxide dismutase, and a decrease in malondialdehyde. Catalase exerted a significant increase with a low dose of A. fragrantissima whereas a high dose had a mild effect. Echinaid and A. fragrantissima raised IgM for the first dose of SRBC and Igs and IgG for the second dose significantly (P<0.05). A. fragrantissima administration ameliorates cytokines (TNF-α, IL-4) and modulated IL-10 significantly (P<0.05). A high dose of A. fragrantissima extract exerted a significant reduction in splenic non-cellular viability% and the highest score of the microscopic immune reaction (immunostimulation+++). Splenic histopathology confirmed the present results. The current study highlights that a high dose of A. fragrantissima extract is preferred over a low dose to restore immune responses in vivo.