"Prescription for Natural Healing" by James and Phyllis Balch is a great resource for this. Under the subheading "Weakened Immune System", for herbs that may help it suggests the following:
Astragalus
Bayberry
Fenugreek
Hawthorn
Horehound
Licorice Root
Red Clover
Ginseng
Echinacea
Gingko biloba
Goldenseal
St. Johns Wort
You should consult the entire listing for precautions and further information on dosage. The book is available for purchase here.
Glutathione is another important piece of the puzzle for balancing your immune system.
Glutathione is known as an immune system optimizer or balancer. It knows what to do, so if you have an immune deficiency, you can raise your glutathione and "boost" your immune system by promoting monoclonal expansion of white blood cells, which your body uses to fight off infection and foreign invaders. The limiting factor in your body's ability to fight off infection is its availability of glutathione.
However, in the case of someone who has an autoimmune disorder, where the immune system is overactive, the last thing you want to do is stimulate it.
Fortunately, glutathione has the ability to cool off the over-activity by re-balancing the components which include the cytokines as well as the T cells and B cells.
The cytokines are inflammatory proteins that in the case of autoimmunity, go around your system "tagging" good guys as bad guys, and then your immune system destroys the good guys by mistake. Glutathione keeps the cytokines honest, so that they only tag good guys good and bad guys bad.
All of this goes on without you even thinking about it.
The human immune system is very complex, but in the case of glutathione, it can be correctly referred to as an immune system optimizer. So whether you are immunodeficient, or you have an autoimmune disorder, or even if you are healthy, you can benefit from glutathione up-regulation.
You can view the list of ways to raise glutathione, which include some natural herbs, drugs, and medicinal foods by clicking here.
Immunocal is the most effective, safe, and natural way to raise and sustain your glutathione.
You can order Immunocal here.