Wild epiphytic Bangladeshi orchids Cymbidium aloifolium (L.) Sw. and Papilionanthe teres (Roxb.) Lindl. potentially modulate the immune functions in Swiss albino mice

Objective: This research investigated the immunomodulatory potentials of two medicinally important wild epiphytic Bangladeshi orchids Cymbidium aloifolium and Papilionanthe teres using Swiss albino mice. Materials and Methods: Orchid extracts were prepared using a cold methanol extraction procedure. To assess the immunomodulatory action, Swiss albino mice of either sex weighing 25-35 gm were divided into five groups each with six animals. Sheep red blood cells (SRBC) of 0.5 × 109 cells/ml were used to immunize all mice on the 7th day, and a booster dose of the same quantity of SRBC was given on the 11th day of the experiment. After 14 days of oral treatment with 100 and 200 mg/kg bw of orchid extract, the mice were sacrificed to collect serum and organs. Hematological assays, delayed type of hypersensitivity assays, phagocytic index (PI), and histopathological investigations were used to assess in vivo immunomodulatory efficacy. Results: The body weight changes of the experimental animals were considerably greater at 100 mg/kg bw than at a higher dose (200 mg/kg bw). There was a substantial improvement of relative organ weights of the thymus and spleen at the low dose, but no effect on kidney weights was evident. The liver weight increased significantly (p < 0.05) at both doses. Total neutrophil, leukocyte, and lymphocyte counts, hemoglobin percentage, delayed hypersensitivity reaction, and PI were all significantly (p < 0.05) increased in mice receiving the lower dose. In contrast to the control group, the higher dose reduced immunological response, suggesting the negative influence of a higher dose of extracts on the immune reaction. Conclusions: The results demonstrate that orchid extracts can potentially modulate the innate immune system in the experimental animal.