Antibody Vs Antigen: Comparisons & Differences

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Getting sick is no fun, and it can take a toll on our busy schedules, especially if all it seems we can do is sleep. When we are sick, while it may seem like we have no energy, our bodies are actually hard at work. When a harmful bacterium or virus enters our body, our immune systems are busy fighting every one of them. Our bodies are experts at making a secret weapon that can take down any intruder. In this article we take a comprehensive look at antibody vs antigen and how our bodies fight to keep healthy.

What Are Antibodies And Antigens?

They may sound similar, but antibodies and antigens play opposite roles in our overall health. While antigens are part of the viruses and bacteria that make us sick, antibodies are the proteins that our immune system makes to fight off these harmful germs. While it's typically antibody vs antigen, the two "antis" have both differences and similarities, and modern science has even allowed us to use antigens in vaccines to help build our antibodies against certain dangerous viruses and bacteria.


In a nutshell, antibodies are proteins our bodies make in response to dangerous and foreign microorganisms that sneak into our bloodstreams or other bodily fluids. Once a foreign substance is identified, an appropriate antibody is created by our immune systems that will bind to that foreign substance to destroy it or tag it so that other members of our immune system will fight it off. They are produced by a specific white blood cell called B-lymphocytes or B-cells.

Antibodies have a distinct Y shape, and the tips of the Y are calledparatope, and each paratope recognizes specific epitopes on the antigen, and this is where they bind to the antigen, and help the body discard them. Antibodies are vital to our immune system, and there are five different antibodies that help keep us healthy.

Antibody Classes

Immunoglobulin G is the most important antibody, as this type circulates through blood and other bodily fluids to protect the body from harmful bacteria, viruses, and other microorganisms. We find immunoglobulin A in saliva, tears, mucus, and other respiratory secretions, and in the urinary tract. This antibody neutralizes harmful bacteria that tries to enter the body. Immunoglobulin M is very similar to the G, but this is a very large antibody, so large that it cannot pass through the membranes of cells.

The last two types of antibodies are immunoglobulin D and E. These are secondary antibodies. E has the important job of detecting allergens that enter the body. It is responsible for the allergic reaction you have to bites, stings, and even snake venom. The immunoglobulin E is also important in detecting malignancies and other inflammatory diseases in the body.


In the battle of antibody vs antigen, the antigen is the villain in the story. Antigens are large protein molecules, and we typically find them on the outside of bacteria or other harmful microorganisms. When they enter the body, they stimulate a response from our immune system. Specifically, they trigger a response from the lymphocytes, or white blood cells. These white blood cells are tasked with fighting off infections. There are two main divisions of antigens, and we discuss these below:


The most prominent division of antigens are those that are foreign to the human body. These antigens are also referred to as heteroantigen, and they are typically attached to viruses or other harmful microorganisms. If these antigens enter the body, they are recognized by our immune systems as being intruders that are not welcome. Some heteroantigen include food allergens, snake venom, and foreign bacteria.

There are antigens that naturally occur in some people's red blood cells. They call these the Rh factor. If your blood type ends with a positive, then you have this factor. This is important during pregnancy because if the baby's blood is Rh positive, and the mother's is negative, the mother's immune system could produce antibodies to attack the baby's red blood cells during child birth. If this is the case, medical professionals take precautions during childbirth to ensure a safe delivery for mom and baby.


This division of antigens is referred to as self antigens or auto-antigens. Unlike division I antigens that can immediately be recognized as the villains in the body, these antigens originate in our own cells. If a person has an autoimmune disorder, it is caused by these antigens. When our own antibodies attack naturally occurring antigens in our cells, it is usually B lymphocytes or T lymphocytes antibodies that attack. Most often these division II antigens are made of proteins and nucleic acids.

Is There A Need For Antibodies And Antigens?

Based on what we know so far, it would seem that while antibodies are the heros of the story, antigens are just trouble makers that must be eliminated. While it is true that antibodies are extremely important for our immune systems, antigens have a role to play in keeping us healthy as well. As noted, antigens trigger our immune system to make the antibodies that fight off the harmful intruders like bacteria and viruses.

Importance Of Antigens

Scientists have used antigens to help our bodies be better prepared when the worst of these harmful microorganisms show up. Through the 19th and 20th centuries, scientists like Louis Pasteur started creating what we know as vaccines. Using new discoveries in bacteriology these scientists could determine that, if presented with dead or near dead bacteria, our immune system would still recognize the antigens on these dead bacteria and viruses and still produce antibodies to fight them.

Then, after creating antibodies to fight the dead cells of diseases like measles, mumps, and rubella, not to mention cholera and even the plague, our bodies would carry a memory of those harmful elements, and then if they ever attacked the body again, our body would immediately make the correct antibody to fight them off before they caused us harm. Thus, vaccines were created and are still used today. They allow our body to prepare for some of the most harmful and deadly diseases, so that if we are ever confronted with them, our antibodies can fight and kill them off before they cause us harm.

Importance Of Antibodies

We have discussed why antibodies are so important. They are the worker bees of our immune systems. These micro-heros are constantly identifying and capturing harmful substances that enter our bodies. Antibodies are so important to our life and health that these proteins are passed from a mother to her baby during pregnancy.

These are known as pre-birth antibodies, and they are passed from a mom to the baby in what's called passive immunization. Once the baby has this first batch of antibodies from the mother, she will start making her own antibodies in response to antigens she comes in contact with. On average the human body can produce over one billion different antibodies to defend against a plethora of antigens it might encounter.

Antibody And Antigen Comparisons And Difference

The Make-Up Of Antibody Vs Antigen

While antibodies are always proteins, antigens can either be proteins, polysaccharides, lipids, or nucleic acids. Even though antigens are typically foreign to the body, our bodies make the division II antigens. Antibodies are always made by our immune systems, and this is in response to antigens it comes in contact with. Each antigen is unique to whatever pathogen or harmful substance it is attached to. This is an important part of the antigen make up because this is how the immune system knows which antibodies need to be made to fight the harmful bacteria and pathogens.

Paratopes And Epitopes

The region of an antigen that interacts with the antibody is the epitopes. These are unique identifiers on each harmful bacteria, and they are normally comprised of five to eight amino acids linked together. They hang out on the surface of the bacteria or other harmful element. This is key because this is how our antibodies recognize and capture the pathogens that could hurt us. The paratopes are located at the two tips of the "Y" of the antibody. They bind and lock on to the epitopes and then dispose of them by either destroying them or tagging them to be destroyed by other elements in the immune system.

Forget Me Not

A very important factor when considering antibody vs antigen is the fact that antigens are unique and distinct to the pathogen they are connected to, and the antibodies produced by our immune systems will never forget it. The antibodies that are made in response to a particular antigen are actually stored in cells called Memory B cells.

When not needed, these antibodies remain dormant, but as soon as that same virus or bacteria, or even one that is similar, attacks the body, these antibodies jump into action. This means that if one string of bacteria makes you sick, the next time it attacks your body will be ready, and you might not even get sick, but if you do your downtime will be minimal, thanks to the great memory of your antibodies.


It's almost as if the antigen was created as the perfect villain for our heros the antibodies. When you think about antibody vs antigen, they compliment each other as worthy opponents. The human body is amazing in so many ways. The fact that we have a tiny army just waiting in our plasma ready and willing to fight off the harmful particles that dare to invade our organs is amazing to think about. 

Bacteremia Vs Sepsis: What Is Similar & What Is Different?

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Healthcare is full of similar terms describing related events in the human body. However, these terms often have different implications to those in the know. Bacteremia vs sepsis is one of these situations. Although the differences are not evident at first glance, the implications are serious and could be life threatening. It is important for all healthcare workers to be able to make this important distinction. With proper understanding, healthcare professionals can properly manage and treat those with these conditions.

What Are Bacteremia And Sepsis?

 Bacteremia and sepsis both refer to bacteria and blood, but there are key differences between the two conditions. Let us first look at the definitions of each.

What Is Bacteremia?

 This term refers to bacteria present in a person's blood. It says nothing as to how much bacteria is present, nor anything about the state of that bacteria. So, when a small amount of bacteria ends up in the blood after one brushes their teeth, for example, this is considered bacteremia. A major infection that floods a body with bacteria and leaks into the bloodstream is also considered bacteremia. Most of the time, there is only a small amount of bacteria which is quickly nullified and excreted. However, since this term can also refer to serious infections, more terminology is required.

What Is Sepsis?

 When the body reacts to bacteria in the blood, symptoms arise such as a fever, rapid pulse and respirations, weakness, and confusion. This is called sepsis and is the result of massive amounts of inflammatory chemicals being released to react to the bacteria. Along with the symptoms, sepsis also has serious consequences as it has an effect on internal organs, such as the heart, lungs, and kidneys. As sepsis progresses, these organs begins to fail. This is why sepsis is a serious condition and also why there is much focus on this term.

What Is Septicemia?

There is one more term related to bacteremia vs sepsis. While bacteremia is bacteria in the blood stream, septicemia is the term used when these bacteria have begun to multiply. This is a much more serious condition than bacteremia, and will generally lead to sepsis. Septicemia can also be referred to as a blood infection. However, in practice, this term is less commonly used.

 Here is one way to look at bacteremia vs sepsis vs septicemia: when bacteria are in the bloodstream, this is called bacteremia. When the bacteria have infected the blood and are growing, this is septicemia. When the bacteria cause enough of an effect to cause the body's immune system to react ferociously, then this is sepsis.

Is There A Need For Different Terms?

All of these terms describe a different medical condition, so bacteremia and sepsis are required. However, there is a difference between medical terminology and communicating with patients. When speaking with other healthcare professionals, specific terminology is required to convey exactly what is occurring within a patient's body. For this to work, all healthcare workers require schooling and training that covers the precise definitions in play. The public does not have this training, yet still need to understand their diseases. So, healthcare professionals may have to describe diseases in different ways.

What Causes The Confusion Between Bacteremia Vs Sepsis?

The confusion between bacteremia vs sepsis comes from how these conditions are commonly described to patients. When people have sepsis, healthcare professionals often describe this as bacteria in the blood or a blood infection. This simplified definition is essentially the same as bacteremia or septicemia. However, this is followed with an explanation as to why this is bad and why it requires immediate treatment. This is really the important information in terms of the patient's health and the information that must be properly understood.

In order to prevent patients from being confused by complicated definitions, all of these terms are boiled down to the basics, and conditions are usually referred to as sepsis. Doctors will say something like this to patients, "Bacteria is in your blood and this is very bad. It needs to be killed or else it could be life threatening." Although this is a simplification, the key information is conveyed to the patient.

How Is Sepsis Treated?

Sepsis is a serious condition that results in over 250,000 deaths a year. For this reason, treatment requires powerful medications. Intravenous antibiotics are commonly used, as well as broad-spectrum antibiotics that kill all types of bacteria. Once the particular bacteria has been identified through a blood culture or other testing, then doctors often switch to a more specific antibiotic. Intravenous fluids are also commonly used within three hours. These treatments usually require patients to be admitted into a hospital, which allows medical staff to constantly monitor their condition.

How Is Bacteremia Treated?

Bacteremia, on the other hand, usually only involves a small amount of bacteria in the blood. This is quickly eliminated by the body's immune system. Because it only stays in the body a short time, no treatment is required. Of course, bacteremia is the first step towards septicemia and potential complications such as septic shock. Also, it is not a specific term and could refer to serious infections. However, understanding bacteremia vs sepsis is that bacteremia conditions usually resolve without medical care while sepsis requires major medical care.

Bacteremia Risks

 Even though most bacteremia is quickly resolved, there are several medical conditions healthcare professionals should be on the lookout for. First, when patients have a urinary catheter, bacteremia can occur if there is a urinary tract infection. Although this is a common cause, any catheter in a patient's body can cause bacteremia. Also, even if sepsis does not occur, conditions such as endocarditis or meningitis can occur with repeated bacteremia. In these cases, bacteremia is treated with antibiotics as soon as it is detected.

What Is Septic Shock?

One serious complication that can occur with sepsis is septic shock. In the life threatening condition, a patient's blood pressure drops and insufficient amounts of blood flow to the organs. This is how organs begin to fail, and this can result in mortality rates of up to 40% is severe cases. This can occur in those with compromised immune systems as well as those with functioning immunity. The key to treating this condition and preventing mortality is early detection and treatment.

Treatment Of Septic Shock

 Like sepsis, antibiotics are required, but other treatments are also key. Vasopressors are often used to raise a patient's blood pressure, keeping mean arterial pressure over 65 mm Hg. Surgery may be performed to remove pus or infected tissue. Oxygen is often provided to patients as well as any machines necessary to support organ systems that no longer function. Methylene blue can also have beneficial effects. Finally, there are multiple stages of fluid replacement used for septic shock.






 Understanding the differences for bacteremia vs sepsis are important for all healthcare professionals. Though a simplified explanation may be sufficient for patients, it is useful for healthcare workers to understand the subtle differences between these terms. Also, even though sepsis requires aggressive treatment while bacteremia generally does not, there are cases where bacteremia alone can be harmful to patients even without progression. Of course, septic shock is a condition to avoid due to its high mortality. With proper understanding of these terms, healthcare workers can provide the best care.

Butterfly Needles: What Are They & Amp; How Are They Used?

Blood tests are one of the most common and important tests for patients in both hospital and outpatient settings. By testing blood, doctors have a quick way to evaluate multiple organs and systems in the body. Not all needles used to draw blood are the same. One good option is the butterfly needle, which can also be used for IV fluids and medications. Although there are some disadvantages, a butterfly needle is generally a safe, effective option for healthcare workers.

What Is A Butterfly Needle?

Classically, a needle is simply a hollow needle that can be attached to a tube or syringe to either remove or insert fluids into the body. Some needles are double sided, with a smaller needle to penetrate the skin and a larger needle to go through a rubber stop and transfer blood into a test tube.

A butterfly separates these two elements. The needle to penetrate the skin is attached to a flexible tube, and this runs to a larger needle that can transfer blood to a test tube. Another variant has an attachment for without the larger needle. On both types there is a double-winged plastic tab near the needle to penetrate the skin. The whole contraption looks like a butterfly, which gave this device its name.

Are There Benefits To Using The Butterfly Needle?

For blood samples, the needle attached to a butterfly tends to be smaller than the standard needle commonly used. Combined with the flexible tube, this tends to make a butterfly more comfortable than standard needles. Also, they are less likely to cause a vein to collapse, making them advantageous for children, geriatric patients, or others with small veins.

Another advantage of this is that smaller veins can be used to obtain samples, such as those on the back of the hand. There are also advantages that a butterfly provides during its use.

Wh​​​​​ile Inserted in a Pa​​​​t​​​​ient

Retractable Needles

IV Use

Butterfly Needle Info And Tips

Although the smaller needle on a butterfly increases comfort, less blood flows through the smaller opening, making blood sample take longer than with standard needles. Healthcare workers should be patient when using a butterfly. 

One tip when using inserting a butterfly needle into a vein is to look for the "flash." This is when a small portion of blood enters the tube attached to the butterfly and tells the healthcare worker that the needle is inside the vein.

One thing to note is that the smaller needle and reduced movement of a butterfly will help decrease bleeding after a blood sample is drawn. This can be very important for patients with a clotting disorder like hemophilia or Von Willebrand disease.

Still, a smaller needle can have disadvantages. 25 or 27 gauge needles are so small that blood could clot inside the needle or blood cells could be destroyed. Fortunately, most butterfly needles are large, at 21 or 23 gauge. Also, a study showed that blood drawn from a butterfly was less likely to be destroyed compared to that when drawn from an IV catheter.


A butterfly needle is an excellent option for healthcare workers who need to access a patient's vein, both to draw blood samples and also to input fluids through an IV. They provide a more comfortable option during blood samples and can be used on smaller, more delicate veins, including those on the back of the hand.

For IV use, the tube attached to the needle can be attached to an IV bag and used for fluids, medications, and other tasks when used for a short timeframe. Healthcare workers should be patient as blood flows more slowly, and they should also watch for the flash of blood when inserting the needle.

Although these are good benefits by themselves, a butterfly needle can also reduce needle sticks. This is an important benefit to protect healthcare workers from being accidentally infected with serious diseases such as HIV and hepatitis B. For this reason, many institutions have begun using a butterfly for all blood draws and eliminating the traditional needles.