My completely naive and unqualified opinion on why antibiotic therapy worked in my case is that some percentage of sarcoidosis and possibly other autoimmune disease like RA is caused by 'internal acne' of some tissues causing runaway inflammation. Minocycline is mostly used to treat skin/face acne but has fallen out of favor because of side effects. IIRC this is because it penetrates deeper into tissues and can cross the blood/brain barrier.