Cosentyx is a biologic drug used to treat certain autoimmune diseases, such as psoriasis and psoriatic arthritis. It is a human monoclonal antibody that selectively binds to and inhibits interleukin-17A (IL-17A), a cytokine that plays a key role in the development of autoimmune diseases [1]. By blocking IL-17A, Cosentyx reduces inflammation and other symptoms associated with autoimmune diseases [2].

Cosentyx can affect the immune system by reducing the activity of certain immune cells that produce IL-17A. This can increase the risk of infections, including serious infections, such as tuberculosis and invasive fungal infections [3]. In clinical trials, patients treated with Cosentyx had a higher incidence of infections compared to those treated with placebo [1].

According to the Cosentyx website, patients taking Cosentyx should be monitored for signs of infection and should not receive live vaccines while on treatment [3]. Patients with a history of chronic infections or immunosuppression should also be carefully evaluated before starting treatment with Cosentyx.

In summary, Cosentyx affects the immune system by blocking the activity of IL-17A, which can increase the risk of infections. Patients taking Cosentyx should be closely monitored for signs of infection and should not receive live vaccines while on treatment [1][2][3].

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/COSENTYX
[2] https://www.drugs.com/medical-answers/cosentyx-weaken-immune-system-3558003/
[3] https://www.cosentyx.com/safety-and-side-effects