Introduction

Human red blood cells (red), activated platelets (purple) and white blood cells - monocyte (green) and T lymphocyte (orange)  This isn't the color they are in the body!

    The function of the immune system is to protect us from infection by a pathogen. First the system has to recognize the pathogen as foreign. Then it must activate non-specific (innate) and specific (acquired) immune responses to remove the pathogen. Besides pathogens, our immune system encounters all sorts of other molecules in the environment that are foreign to our body, but not infectious and not harmful to our health. These substances (allergens) do not activate the immune systems of most people. But some people’s immune systems do respond to an allergen, and they develop an immune response to it, just as they might to a foreign antigen. Their immune system overreacts, and the person may feel sick, as if their body is fighting off an infection, even though there isn’t one. We often describe these individual as having an allergy or hypersensitivity.

Today you’ll play "doctor" and diagnose the condition of your "patient" Jane Smith. In the process you’ll learn about how the immune system works and actually perform two immunological tests that a doctor might order to help make this diagnosis.

Jane’s History

Jane Smith is a 16 year-old high school junior who is highly motivated as an athlete and academic student.  She has had a history of good health until this past semester.  Her life style hasn't altered too much in terms of eating habits, hobbies or time for sports and school. But lately, she’s so tired that she collapses in bed after coming home, unable to complete her homework.  She’s having trouble sleeping at night, so that during the day, she has trouble paying attention in class and is afraid her grades will suffer, putting her college plans in jeopardy.  Jane has also noticed that she is short of breath on occasion and rather "stuffed up" some evenings, especially after she comes home from her new job, babysitting next door at the Haynes’s, which she does 3 evenings a week. She doesn’t have a fever. She reported to the school nurse twice this week, complaining of a bad cold. At her second visit, the nurse suggested that she should see you, her pediatrician, since it seemed that there hadn’t been any improvement in how she was feeling. The nurse suggested that maybe she didn’t have a cold but that she might have an allergy. But she has a pet cat, Mildred, and isn’t allergic to her, and there aren’t any cats at the Haynes’s, just a dog and a parrot. So she really doesn’t think she has an allergy.

Results of Jane’s clinical examination

Jane is a 16 year-old female, in no acute distress. Her vital signs are: Temperature 98.4 degrees, pulse 72, blood pressure 116/74, respiratory rate 16. Jane has dark circles under both her eyes. Her sclera (the whites of her eyes) are red, but there is no discharge. Her ears are normal. Her nasal mucosa are pale, with a clear discharge, suggestive of allergies. Her mouth is normal, and her tonsils aren’t enlarged. There is no tenderness over her sinuses. Her neck is supple, with no swollen lymph nodes. Her heartbeat is regular, without any murmurs. Her lungs showed scattered wheezes when she breathed out. Her abdomen is soft, with no masses or organ enlargement. No rashes were present.

You order a routine set of tests to evaluate her overall health. Decide whether the results are normal, and record your evaluation for each test in the column marked "Your Evaluation".