Why is an antimalarial drug, hydroxychloroquine, used as a rheumatological immunosuppressant in disorders such as systemic lupus erythematosus (SLE)?

Hydroxychloroquine (HCQ), originally developed as an antimalarial, has become a cornerstone in the treatment of autoimmune diseases, including systemic lupus erythematosus (SLE), primary Sjögren’s syndrome, and rheumatoid arthritis. How does this drug help address the challenges posed by these autoimmune diseases?

1. Interference with lysosomal activity and autophagy:
HCQ increases the pH within intracellular lysosomes, interrupting the autophagy of macromolecules and antigen processing in antigen-presenting cells. This leads to diminished T cell stimulation, providing an advantage in autoimmune conditions like SLE by modulating immune responses. Continue reading