What is Type II Hypersensitivity Reaction?
Type II hypersensitivity reaction is a type of immune response where specific proteins in our body called antibodies (either IgG or IgM type) target substances that our body perceives as foreign. These foreign substances can be on the surface of our cells or in the spaces between cells. The reaction of these antibodies can cause the cells to be destroyed, lose functionality, or lead to damage in our tissues. This damage can happen in three different ways:
1. The antibodies can attach to receptors on the cell surface and change their activity.
2. The antibodies can activate something known as the complement pathway, which is a part of the immune system that enhances the ability to fight off and remove harmful substances.
3. The antibodies can trigger a response called antibody-dependent cellular cytotoxicity – this is a complicated way of saying certain cells are triggered to kill others.
What Causes Type II Hypersensitivity Reaction?
Type II hypersensitivity reaction is a response from your immune system when it believes that certain parts of your cells have been changed in some way. This reaction is often triggered by certain medicines like penicillin, thiazides, cephalosporins, and methyldopa. These medicines can either attach themselves to the surface of the cells or alter the existing parts of the cells that the immune system uses to identify what is ‘self’ or ‘foreign’. This misleads the immune system into thinking the modified cells are foreign, resulting in the production of antibodies against your own cells.
Usually, your immune system has a mechanism, called immune tolerance, that allows it to tell apart its cells and not to launch an an attack against them. However, certain factors can interfere with this mechanism, leading the immune system to produce antibodies against its own cells.
Risk Factors and Frequency for Type II Hypersensitivity Reaction
There isn’t a lot of data available about hypersensitivity reactions, which are an adverse response to certain drugs. Despite this, about one-third of all negative drug reactions are believed to be hypersensitivity reactions. These reactions can be dangerous, potentially causing death or extending hospital stays. There are not yet established links to genetic factors, but future genetic studies could potentially identify those more at risk. The frequency of these reactions can also vary depending on the specific circumstances, such as a different type of hypersensitivity reaction like the hemolytic disease of the newborn. This rare condition affects Rh-negative women giving birth, with approximately 1 to 3 out of every 1,000 affected even with advanced treatment methods.
Signs and Symptoms of Type II Hypersensitivity Reaction
People living with type II hypersensitivity reactions may have different experiences and symptoms, depending on the kind of disease they have. When asked about their medical history, patients might talk about having had a lot of blood transfusions, issues with blood type or rhesus incompatibility, or recent use of specific medications. It’s also possible that they might show signs of an autoimmune condition. This means their body’s immune system is attacking its own cells. Examples of these kinds of conditions include immune thrombocytopenia, which may cause bleeding disorders; autoimmune hemolytic anemia, which can lead to jaundice; and autoimmune neutropenia.
In the case of a disease called myasthenia gravis, patients may experience general weakness in their muscles. This could make it difficult for them to move around, eat, speak, or perform routine tasks.
Testing for Type II Hypersensitivity Reaction
If you find yourself dealing with severe allergic reactions, your doctor might want to determine the causes and the extent of these reactions. This typically depends on what triggered the reaction and a mix of your symptoms and test results to make the correct diagnosis.
Understanding certain reactions caused by antibodies in your body is very important. For example, one common type of these reactions is when you get a reaction after taking a certain medication, which can result in a condition known as drug-induced lupus. In cases like this, your body might produce too many antibodies targeting your red blood cells because of the drug, causing the condition.
How does your doctor evaluate these reactions? You’ll first need some blood tests to measure your red and white blood cells, as well as your platelets, in case the numbers are too low. These blood tests will also check for proteins called immunoglobulins, which are part of your immune system. Some tests might be specific, looking for proteins such as IgG, IgM, and IgE, depending on the type of allergic reaction they are investigating.
Further tests can be done to identify what kindof things are causing the allergic reactions. For example, you might be tested for allergies to animals, plants, foods, and environmental factors, using skin prick tests. Another test is the radioallergosorbent test (RAST) to check for a specific immune protein (IgE).
Reactions to drugs can also be determined by injecting small amounts of the suspected drug into the skin to see if there’s a reaction. For example, this is commonly done for suspected allergies to drugs like ceftriaxone and carbamazepine.
Doctors may also evaluate the presence of autoantibodies, which are antibodies that mistakenly target and react with a person’s own tissues or organs. These autoantibodies can be present in autoimmune diseases, like lupus and rheumatoid arthritis. Tests that look for autoantibodies can also help in diagnosing conditions targeting specific organs, like diabetes mellitus that targets the cells producing insulin in the pancreas, certain kinds of thyroid diseases, and myasthenia gravis, a condition that weakens your muscles.
Treatment Options for Type II Hypersensitivity Reaction
The treatment after diagnosis will vary based on the specific guidelines and advice for each type of disease. If the condition was caused due to a particular reason like an adverse reaction to a medication, or specific diseases like hemolysis (a condition where red blood cells are destroyed) or drug-induced autoimmune diseases (where the body’s immune system mistakenly attacks its own cells), it’s crucial to avoid whatever caused the issue. The management of low blood cell counts should also be set according to a specific plan. Giving a person systemic glucocorticoids, a type of steroid that can help reduce inflammation and the body’s immune response, is another significant way to stop the body from making antibodies and prevent damage to tissues.
Here are a few examples of specific treatment plans for different scenarios:
If an adverse reaction to a medication, a type of drug-related lupus (an autoimmune disease that causes inflammation), or low blood cell counts are caused by a particular drug, then that drug should be stopped.
If someone has acute rheumatic fever, a bacterial infection that can affect the heart, joints, skin, and brain, they should start taking antibiotics to get rid of the bacteria that causes it (group A streptococcus). Penicillin V and benzylpenicillin are primarily used for this. If the patient is allergic to penicillin, oral cephalosporins, another type of antibiotics, can be used as an alternative. Treatments for specific symptoms, like arthritis (joint pain and inflammation) or carditis (inflammation of the heart), should also be provided. In preventing future damage to the heart, the patient should be given treatment to prevent future infections caused by group A streptococcus. Benzathine penicillin G is the drug of choice for this preventive care.
Sometimes, the immune system can attack the thyroid gland, leading to a condition called Graves’ disease that can make the thyroid overactive. In this case, antithyroid drugs, including propylthiouracil and methimazole, are given. Also, destroying the thyroid gland with radioactive iodine or removing it surgically should also be considered. Glucocorticoids are used to treat the eye problems that can come along with Graves’ disease.
For myasthenia gravis, a condition where muscles become weak, medications like acetylcholinesterase inhibitors such as pyridostigmine are prescribed. If pyridostigmine doesn’t work, a different type of medication called immunosuppressive therapy (like corticosteroids) can be used. Surgery to remove the thymus gland (known as thymectomy) is considered if medication doesn’t work. If the patient is having a myasthenic crisis, a severe bout of muscle weakness, plasma exchange and intravenous immune globulin might be needed.
What else can Type II Hypersensitivity Reaction be?
When trying to identify what’s causing type II hypersensitivity reactions, doctors have to take into account the specific symptoms that come with each type of disease. It’s also important to understand the different kinds of hypersensitivity reactions and what kind of health problems they usually lead to.
Here are some of the most common conditions that might be causing these reactions:
- Anemia due to the breakdown of red blood cells (hemolytic anemia)
- Low counts of certain blood cells (cytopenias), like platelets (thrombocytopenia) or white blood cells (neutropenia)
- Reaction to certain medications (drug toxicities)
- Conditions where the body’s immune system attacks its own cells (autoimmune diseases)
- Allergies
- Infections
- Problems with the body’s hormone-producing glands (endocrinopathies)
- Conditions that affect the muscles and nerves (neuromuscular disorders), such as those that are passed down through families, result from wear and tear on the body, are caused by inflammation, result from medical interventions, are caused by tumors (neoplastic), or occur when the body’s immune system targets the nerves and muscles (autoimmune)
- Problems with the heart’s valves (valvular heart disease)
What to expect with Type II Hypersensitivity Reaction
The future health outcome (or prognosis) of reactions caused by type II hypersensitivity – when the body’s immune system attacks its own cells – largely depends on timely diagnosis and carefully ruling out other potential diseases or conditions. The prognosis can also differ depending on the specific disease in question.
For example, the overall outlook for hemolytic disease of the newborn, a type of blood disorder, is generally good if it is detected and treated promptly. In the case of myasthenia gravis, a condition that causes muscle weakness, most patients can live a nearly normal life span with modern treatments.
It’s worth mentioning that treatment advancements have vastly improved the prognosis for some conditions. For instance, fifty years ago, a severe form of myasthenia gravis called ‘myasthenic crisis’ had a mortality rate of 50% to 80%. Now, thanks to improved medical treatments, the mortality rate has dropped significantly to 4.47%.
Possible Complications When Diagnosed with Type II Hypersensitivity Reaction
If medical conditions are not promptly addressed, they can cause damage to one’s tissues or organs. This largely depends on the symptoms and signs apparent in the patient. For example, a decrease in all types of blood cells could lead to infections, a propensity to bleed, and severe types of anemia. Acute rheumatic fever, a disease that can result from poorly treated strep throat or scarlet fever, might pave the way for rheumatic heart disease, causing lesions on the heart valves. A severe condition called myasthenia crisis (a severe worsening of symptoms like muscle weakness) can be life-threatening if not treated correctly with a procedure to help with breathing and anti-inflammation medicine.
Dangers of Untreated Medical Conditions:
- Tissue or organ damage
- Infections due to decreased blood cells
- Tendency to bleed excessively
- Severe types of anemia
- Heart disease caused by acute rheumatic fever
- Life-threatening Myasthenia crisis
Preventing Type II Hypersensitivity Reaction
It’s crucial for patients to understand their diagnosed condition and how important it is to take their prescribed medications consistently. This helps prevent severe, potentially life-threatening complications. Patients should also be urged not to start any new medications without first discussing it with their doctor or healthcare professional. If a patient has been diagnosed with a condition known as myasthenia gravis, they should make sure to follow their treatment plan closely. By doing so, they can help keep the disease under control and prevent it from getting worse.
