RA occurs when the body’s immune system mistakenly attacks the lining of the joints, causing stiffness, pain, and warmth. A 2019 review article states that RA affects the lymph nodes ...

A lymph node biopsy is when a doctor checks and removes a small piece of tissue or sample of cells from one of your lymph nodes. The doctor sends this to the laboratory and a specialist doctor called ...

Medically reviewed by Daniel More, MD Allergies occur when your immune system overreacts to allergens like pet dander, pollen, mold, certain foods, or medications. Allergy symptoms may include a runny ...