Easily summarize the four types of hypersensitivity reactions: mechanism and representative disease comparison

Hypersensitivity refers to a condition in which the immune response that guards the body is not excessive or harmful, or rises up towards the tissues of the body and causes tissue damage or disease. Usually, according to the mechanism, it is divided into four types from Type I to Type IV.

In adult nursing, pathophysiology, and national notice preparation, the question of pairing type and disease frequently appeared, and the mechanism and representative diseases were easily compared. This article is a study summary, and the diagnosis or treatment should follow the judgment of the medical staff.

Ⅰ How will type I hypersensitivity reactions occur?

Type I is called immediate or anaphylactic. When exposed to allergens for the first time, IgE antibodies are made and attached to mast cells, and when the same substance enters again, substances such as histamine quickly come out of the mast cells and cause symptoms. Allergic rhinitis, urticaria, bronchial asthma, and anaphylaxis are typical diseases. Concepts for each type can also be found in the Immune Hypersensitivity Reaction Wiki article.

Since type I contains anaphylaxis, which has the fastest reaction rate and can be life-threatening, it is frequently asked for along with emergency measures in tests.

What is the difference between Ⅱ and Ⅲ?

Both types involve IgG or IgM antibodies, but they have different ways of attacking. Type II (cytotoxicity) is a reaction in which an antibody attaches directly to an antigen on the surface of a cell and destroys the cell. Incompatible blood transfusion reactions, hemolytic neonatal disease, and autoimmune hemolytic anemia are typical. Type III (immunocomposite type) is a reaction in which the immunocomposite combined with antigen and antibody builds up in the blood vessel wall or tissue, activates the complement, and causes inflammation. Systemic lupus erythematosus, glomerulonephritis after streptococcal infection, and seropathy are representative.

These two types are the most confusing part of the trial because the antibodies involved are the same, so it is good to make a table based on where the antigen is.

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Why is Type IV called delayed?

Type IV is not an antibody, but a cell-mediated immune response centered on sensitized T-lymphocytes. It takes time for T cells to recognize the antigen and send out various substances to collect macrophages, so it is called delayed because the reaction usually occurs 24 to 72 hours after exposure. Tuberculosis skin reaction test (tuberculin test), contact dermatitis, and transplant rejection are typical.

How will I be organized in the exam?

Once you have created the table, cover the name of the disease and test yourself by looking only at the mechanism and matching the type. Conversely, if you practice thinking of representative diseases in two or three ways based on the type alone, you won't be shaken by asking in any direction in the problem. It's a good idea to collect confusing diseases and write down the reasons one line at a time for why they are the type.

It can be compared at a glance by grouping the four types into a single table with the name, the immune elements involved (IgE, IgG, IgM, immunocomplex, T-cells), the response time, and the four columns of representative diseases. If the problem comes up with a name, it helps to practice thinking backwards. If you ask for nursing intervention together, it is good to add core nursing for each type, such as maintaining airways and preparing emergency medications, and avoiding causative agents for type IV. In addition to the four types of innate immunity, acquired immunity, and hypersensitivity reactions, and the mechanism of occurrence of representative diseases, the campus-down hypersensitivity response, TNM, and DIC nursing summary data, which is summarized on page 12, the TNM classification of tumors, the DIC generation mechanism, and the warfarin-administered nursing care, can be used as a reference for those preparing adult nursing assignments and national examination reviews. Please check back with the latest manuals and instructions for clinical readings and medication information.