Chloroquine is useful in:
Hydroxychloroquine​
Hydroxychloroquine is used for early, mild RA, often combined with methotrexate. This agent is also used in the treatment of lupus and malaria. Its mechanism of action in auto-immune disorders is unknown, and onset of effects takes 6 weeks to  6  months.
Monotherapy may be initiated with any of the DMARDs (methotrexate, leflunomide, hydroxychloroquine or sulfasalazine) for patients with low disease activity.​
​DMARDs = Disease modifying Anti-Rheumatic Drugs.
Reference: Lippincott Illustrated Reviews: Pharmacology Wolters Kluwer Sixth Edition page no 457,458​
Discoid lupus erythematosis
Rheumatoid arthritis
Infectious mononucleosis
All of the above