Start reviewing and responding to the postings of your classmates as early in the week as possible. Respond to all of the initial postings from your peers in your discussion group on different days of the week.

Peer 1

Initial Post:  Answer the following questions about Anna Sanchez and her condition. 

1. What evidence suggests that Anna does not have an acute severe infection?

Anna’s vital signs are within normal limits, her blood pressure and pulse are all normal. Acute severe infections however cause low body temperature, chills, fevers and nausea, among others. 

1. If Anna has allergic rhinitis, what type of hypersensitivity reaction is involved? 

It looks to be that Anna has an Immediate (Type I) hypersensitivity. This type of reaction can also be called an Anaphylactic Response. These reactions are mediated by IgE that are produced as a response to certain allergens. These antibodies bind to mast cells. The most common reactions are caused by food allergies and other allergens in the environment. (Vaillant, 2020)

1. A skin test indicates that Anna is allergic to cat dander. Two months ago, Anna’s roommate brought home a cat. Why didn’t Anna’s symptom start when the cat entered the household, rather than 3 weeks later? 

Sometimes it takes a while for the body to react to certain allergens, also her type of reaction (type I) is delayed because Anna’s body began sensitizing to the allergens in cat dander. Also, it might have taken a while for the cat to shed enough dander to a level that her body could recognize.  

1. What class of antibodies bind to the mast cells? 

The class of antibodies that bind to mast cells are called IgE (IgE | Biochemistry, n.d.)

1. What physiological mechanisms caused the redness of Anna’s nasal mucosa? 

The cat dander allergens bind with the IgE antibodies on the mast surface which caused the mast cells’ degranulation. The degranulation releases inflammatory mediators which can cause redness. (Krystel-Whittemore, 2016)

1. What mechanisms caused Anna’s clear postnasal drainage? 

Certain mediators like, histamine is released due to mast cell degranulation can cause vasodilation. These mediators promote nasal mucus secretion, this leads to drainage. 

IgE | biochemistry. (n.d.). Encyclopedia Britannica. Retrieved April 1, 2021, from https://www.britannica.com/science/IgE

Krystel-Whittemore, M. (2016). Mast Cell: A Multi-Functional Master Cell. Frontiers. https://www.frontiersin.org/articles/10.3389/fimmu.2015.00620/full

Vaillant, J. A. A. (2020, December 30). Immediate Hypersensitivity Reactions. PubMed. https://pubmed.ncbi.nlm.nih.gov/30020687/

Peer 2

Initial Post: Answer the following questions about Anna Sanchez and her condition.

    Itchy skin, nasal inflammation with watery nasal discharge, “tickling” cough at night, sneezing, and even polyps in her nose all point to allergic rhinitis, according to her medical records. Sneezing, nasal pruritus, airflow obstruction, and mostly clear nasal discharge are all signs of allergic rhinitis, which is caused by IgE-mediated reactions to inhaled allergens and involves mucosal inflammation driven by type 2 helper T (Th2) cells. Her flaking erythematous rash on the flexor surfaces of both arms, which is common in young people with allergies. 

1. What evidence suggests that Donna does not have an acute severe infection? 

All vital signs were all within normal ranges. You’d expect to see a rise in temperature and a spike in respiration. Her nasal drainage also was clear. Infection will be suggested by gloomy, gray, or even yellow drainage. 

2. If Anna has allergic rhinitis, what type of hypersensitivity reaction is involved? 

Most common allergies are Type I reactions. Type I reactions are mediated by antigen specific IgE and the products of tissue mast cells (McCance & Huether, 2014). 

3. A skin test indicates that Anna is allergic to cat dander. Two months ago, Anna’s roommate brought home a cat. Why didn’t Anna’s symptoms start when the cat entered the household, rather than 3 weeks later? 

Anna was being sensitized to the allergens in cat dander during the symptom-free period following her initial exposure to cat dander. Her B lymphocytes were developing antibodies that attached to the mast cell’s outer surface. 

4. What class of antibodies bind to the mast cells? 

Cat dander allergens bind to IgE antibodies on mast cells, allowing antigen to come into contact with the nasal mucosa and leading to crosslinking of immunoglobulin E (IgE) receptors on mast cells. 

5. What physiological mechanisms caused the redness of Anna’s nasal mucosa? 

When IgE binds to mast cells, a cascade of chemicals are released. Histamine, one of the chemicals, triggers skin redness and swollen membranes by opening blood vessels. When this happens in the nose, it causes sneezing and congestion. 

6.What mechanisms caused Anna’s clear postnasal drainage? 

T helper (Th)2 T cells infiltrate the nasal mucosa and release cytokines (e.g., interleukin [IL]-3, IL-4, IL-5, and IL-13) that promote the development of immunoglobulin E (IgE) by plasma cells. The release of mediators such as histamine and leukotrienes, which cause arteriolar dilation, increased vascular permeability, itching, rhinorrhea (runny nose), mucous secretion, and smooth muscle contraction, is triggered by IgE development. 

References 

McCance, S.H. K. Pathophysiology. [South University]. Retrieved from https://digitalbookshelf.southuniversity.edu/#/books/9780323583473/