What do they do?
One type of professional in the field of the immune system are immunologists. According to the American College of Allergy Asthma and Immunology, the article says "Immunologists are doctors trained to find out what is going wrong with the immune system and how to treat it." Immunologists are also known as allergists. You might see an immunologist if you have food or seasonal allergies. Clinical immunologists diagnose children and adults, which help them with their disorders.
What is required?
To be an immunologist you need a bachelor's degree (4 years), have gone to medical school (4 years), a 3 year residency in internal medicine or pediatrics and a 2-year allergy/immunology fellowship. In total this requires 13 years of training and schooling. If you want to be a research immunologist you need a PHD in immunology, which is 17 years total.