Provided are methods and compositions for increasing CD4+ cell count in mammals, preferably by at least 25%, while undergoing treatment for various conditions whose treatment can have detrimental effects on immune system function. Such conditions include, but are not limited to, HIV infection, cancer, and hepatitis. The compositions include alpha lipoic acid; acetyl L-carnitine; N-acetyl-cysteine; and optionally: zinc, selenium, vitamin C, bioflavinoid complex, vitamin E, co-enzyme Q10, glutathione, beta-carotene, vitamin A, vitamin B1, vitamin B2, vitamin B6, niacinamide, calcium pantothenate, folic acid, vitamin B12, copper, manganese, chromium, and molybdenum.