Effect of aqueous infusion of Plectranthus amboinicus (LOUR) Spreng leaves on humoral immune system in rats

Purpose: To examine the effect of an aqueous infusion of Plectranthus amboinicus (AIP) on the immunological development of rats in response to Bacille  Calmette-Guerin (BCG) antigen induction. Methods: Twenty-four male rats, aged 3 months, were separated into six groups. Group 1 was normal control group without treatment, whereas groups  2 and 3 were the treatment groups induced with 100 μL BCG on days 7 and 14, followed by oral administration of AIP at doses of 19 and 31.5 g/kg, respectively. Groups 4 and 5 were treated only with AIP at doses of 19 and 31.5 g/kg respectively. Group 6 was a negative control group induced with 100  μL BCG on days 7 and 14. On day 31, IgG activity, antibody titer, lysozyme activity, relative organ weight, and lung histology were determined. Results: The results showed that IgG levels, antibody titers, and lysozyme activity were significantly elevated in groups 4, 5, and 6 compared to normal  control group (p < 0.05). Aqueous infusion of Plectranthus amboinicus and BCG had no effect on the relative weight of spleen. However, the therapy administered to rats in group 3 significantly increased their liver and lung mass (p < 0.05). Conclusion: Aqueous infusion of Plectranthus amboinicus  leaves stimulates the immune system in BCG-induced rats.