Be good to your immune system. Feed it lots of raw fruits and vegetables, organic if at all possible. Make sure to get a good source of essential fatty acids - omega's 3, 6, and 9's. (A handful of roasted pumpkin seeds every day is an excellent way to meet ALL of your omega needs.) Stay away from artificial sweeteners and partially hydrogenated and fully hydrogenated foods. Drink plenty of fresh pure water. make sure to get at least 20 minutes of even gentle exercise everyday - walking is great for that. Also try to get 15 - 20 minutes of sunshine every day. make sure to find something to laugh at everyday - 10 minutes of good belly laughter per day per person should be a minumum requirement for healthy living!
You might want to consider starting a regimen of supplements: I recommend these to begin:
selenium: 200 mcg/day (can start with 400mcg/day but only for a few weeks)
magnesium: 200 - 250 mg/day (350 mg/day max), take with food
zinc: 50 mg/day (can start with 100mg/day but only for a few weeks), take with food
manganese: 10 - 15 mg/day, take with food
calcium: 1200 mg/day
We need Vitamin D-3 to be able to absorb and utilize calcium. Our bodies manufacture D-3 if we get adequate sunlight (15 - 20 minutes exposure/day) - but I do not believe in leaving this to chance, so also recommend a Vitamin D-3 supplement, 1000 - 2000 iu/day (10,000 iu/day max)
Find a naturopathic practitioner in your area, and get a consult on nutrition, supplementation and herbal/botanical remedies. A naturopathic physician or nutritionist would be best, but you can get wonderful guidance from other holistic people - herbalists, homeopaths, osteopaths, people who practice ayurvedic or traditional chinese medicine, accupunturists, etc. Best to find someone locally who can help you tailor a plan to best suit your needs.
When the immune system breaks down, it's often because we just aren't getting enough of the basic nutritional building blocks we need to hold it together. The 6 I listed are key elements to good health. As I said, that would be a good start - if you only try one thing, get started taking some selenium and some zinc.
Sincerely,
Tre