Cyclosporine is widely used in the medical field, primarily as an immunosuppressant. It plays a crucial role in preventing organ rejection in transplant patients by suppressing the immune system's response to foreign tissues. This makes it a key component in post-transplant therapy for kidney, liver, heart, and other organ transplants.

Additionally, cyclosporine is employed in the treatment of autoimmune diseases. It is effective in managing conditions such as severe rheumatoid arthritis, psoriasis, atopic dermatitis, and Crohn's disease, where it helps to reduce inflammation and control symptoms by modulating immune activity.

In ophthalmology, cyclosporine is used in eye drop formulations to treat chronic dry eye disease and autoimmune conditions like uveitis. It helps increase tear production and reduces inflammation on the ocular surface, providing relief for patients with these conditions.

Its immunosuppressive properties also make it valuable in research settings, particularly in studies involving immune system regulation and transplantation biology. Overall, cyclosporine's ability to modulate immune responses has made it a versatile and essential drug in various therapeutic areas.