Question

A mother brings her three-year-old son into the emergency room of a local hospital. The boy is crying hysterically. The mother says that earlier that day the boy was playing in the back yard with his older sisters. He had gone over to pick a rose off of a rosebush when he suddenly started screaming and crying. There is a region of swelling and redness on his arm and the doctor who examines him says that it looks like the boy was stung by a bee. On physical examination, he is afebrile, with a heart rate of 102 bpm, blood pressure of 90/62 mm Hg, and respiratory rate of 24 breaths per minute and has difficulty breathing. The doctor says that the boy appears to be having a severe allergic reaction to the sting, and he treats him with SC Epinephrine. The mother asks why her son’s arm is swollen and the Dr. says it is because of fluid accumulation.

1. Describe the process of inflammation that might have led to swelling? 2. Enumerate the mediators of pain, edema, and redness? 3. Describe the vascular and cellular changes during inflammation? 4. Mention the type of shock the child is presented with and Why epinephrine is an ideal choice in this setting and elaborate its mechanism of action? 5. Plot the Drug response curve (DRC) of Epinephrine (Agonist) with and without the presence of Beta-blocker (antagonist). 6. What type of hypersensitivity reaction is seen in this child? This type of hypersensitivity reaction is due to the crosslinking of which immunoglobulin on mast cell surfaces? 7. Which cytokines promote class switching of B lymphocytes to IgE?

Answer 1

When a bee stings, its sharp, barbed stinger remains lodged in the skin. This stinger can release venom for up to a minute after the bee has stung.Bee venom contains proteins that affect the skin cells and immune system, resulting in pain and swelling at the site of the sting, even if a person is not allergic to the venom.In those who are allergic to bee stings, the venom triggers a more severe immune system reaction. These people may not have an allergic reaction the first time they are stung but may have an allergic reaction to a second bee sting.If a person is allergic, the bee sting will cause the immune system to produce antibodies called Immunoglobulin E (IgE). Usually, IgE protects the body from dangerous substances, such as viruses and parasites.However, in response to a sting, the body produces IgE that causes an inappropriate immune responses, such as hives, swelling, and respiratory problems, the next time a person is stung.

The symptoms of a bee sting allergy vary depending on how allergic the person is. A person can have a mild, moderate, or severe reaction shortly after being stung by a bee:

Mild reaction

The majority of bee sting symptoms are very mild and do not require medical attention. They are limited to the site of the sting itself, and include:

• a sharp, burning pain
• an area of raised, red skin
• slight swelling

Moderate allergic reaction

In a person with a moderate bee sting allergy, the body has a stronger response to bee venom, called a large local reaction (LLR). In such cases, the symptoms can take over a week to heal completely.

Symptoms include:

• severe redness around the sting
• swelling around the sting, which may gradually increase in size to a diameter of 10 cm or more over a period of 24–48 hours

If a person experiences a LLR, there is a 5 to 10 percent risk that they will develop a systemic reaction to a sting in the future.

Severe allergic reaction

In certain individuals, a bee sting can cause anaphylaxis, which is a life-threatening allergic reaction requiring emergency medical treatment. The following symptoms of anaphylaxis develop rapidly:

• itchy, red hives on the skin
• pale or flushed skin
• a swollen throat or tongue
• difficulty breathing
• abdominal pain
• nausea and vomiting
• dizziness
• a weak, rapid pulse
• loss of consciousness

Anaphylactic shock occurs during a bee sting.The treatment measures involves use of epinephrine auto injector.

Epinephrine autoinjector

If you're allergic to bee stings, your doctor is likely to prescribe an emergency epinephrine autoinjector (EpiPen, Auvi-Q, others). You'll need to have it with you at all times. An autoinjector is a combined syringe and concealed needle that injects a single dose of medication when pressed against your thigh. Always be sure to replace epinephrine by its expiration date.

Be sure you know how to use the autoinjector. Also, make sure the people closest to you know how to administer the drug — if they're with you in an anaphylactic emergency, they could save your life. Medical personnel called in to respond to a severe anaphylactic reaction also may give you an epinephrine injection or another medication.

• Systemic anaphylaxis: In some individuals, a severe reaction occurs within minutes, leading to symptomatology such as acute asthma, laryngeal edema, diarrhea, urticaria, and shock. Classic examples are penicillin allergy and bee sting allergy.

After activation by antigen, these B cells proliferate. If these activated B cellsencounter specific signaling molecules via their CD40 and cytokine receptors (both modulated by T helper cells), they undergo antibody class switching to produce IgG, IgA or IgE antibodies.