Autoimmune Neutropenia (AIN): The Blood Disorder Where Your Immune System Destroys Its Own Germ-Fighting Cells — and How It's Treated
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD. Last reviewed October 13, 2026. This content is for educational purposes and is not medical advice.
Quick Answer
Autoimmune neutropenia (AIN) is a blood disorder in which antibodies attack neutrophils, the white blood cells that destroy bacteria and fungi [1]. Primary AIN mainly affects infants, while secondary AIN, triggered by another condition, affects older children and adults [1]. It often causes no symptoms, or repeated infections [1]. Mild cases may only need monitoring; treatments include antibiotics, G-CSF and corticosteroids [1].
What the research says
Primary AIN is usually mild, and diagnosing it often takes more than an antibody test. In a retrospective cohort of 3,488 children admitted to one hospital over 3 years, primary AIN accounted for 18 cases (about 0.5%), with a median age at onset of 7.5 months. Neutropenia was severe at some point in 72% of these children, half needed hospitalization, but only 3 had severe infections, and 22% received on-demand G-CSF. In 7 of the 18 children (39%), both antibody tests (GIFT and GAT) were negative, and the authors note that primary AIN is usually diagnosed by excluding other causes (Jinca et al., Experimental and Therapeutic Medicine, 2021) [4].
AIN is the most common neutropenia in young children and is usually benign. A review describes primary autoimmune neutropenia of infancy as the most frequent type of neutropenia in children under 3 to 4 years of age, in most cases with a benign, self-limited course. Diagnosis rests on finding indirect antineutrophil antibodies, which the authors say is frequently difficult (Farruggia and Dufour, Therapeutic Advances in Hematology, 2015) [2].
In adults, a low neutrophil count is often a sign of another condition. An expert review explains that many mild-to-moderate neutropenias signal underlying disorders that need their own treatment, such as HIV, hepatitis, autoimmune disorders, and large granular lymphocyte syndrome, and it offers a stepwise approach to evaluating a newly found neutropenia (Palmblad et al., Expert Review of Hematology, 2016) [3].
What is autoimmune neutropenia (AIN)?
Autoimmune neutropenia (AIN) (pronounced "noo-troh-PEE-nee-uh") is a blood disorder that involves your immune system attacking your body's neutrophils, a type of white blood cell. Neutrophils are an essential part of your immune system. They destroy harmful bodily invaders that cause infections, like fungi and bacteria [1]. With autoimmune neutropenia, your immune system mistakenly attacks these white blood cells. As a result, you have a lower-than-normal level of neutrophils in your blood [1].
Your body's defense against germs works like a supply line: your bone marrow produces neutrophils, they patrol your blood and tissues [5], and they destroy invading bacteria and fungi. When antibodies turn on those same cells, the supply drops, and your infection-fighting power drops with it.
AIN may be primary or secondary.
Type | Who it affects | How long it lasts |
Primary autoimmune neutropenia | Primarily infants and toddlers | Usually resolves on its own within a few years |
Secondary autoimmune neutropenia | Older children and adults | Usually chronic (long-lasting) |
Primary autoimmune neutropenia involves a low neutrophil count that can't be explained by other causes. It mainly affects infants and toddlers and usually resolves on its own within a few years [1].
Secondary autoimmune neutropenia involves a low neutrophil count resulting from another condition, including infections, blood disorders, and other autoimmune diseases. It most commonly affects older children and adults, and is usually chronic, meaning long-lasting [1].
How low do your neutrophils have to be to be neutropenia?
Autoimmune neutropenia is just one type of neutropenia. Neutropenia means your neutrophil count is below normal, and it's classified as mild, moderate, or severe depending on how many neutrophils are in a microliter (microL) of blood [1].
Severity | Neutrophils per microliter (microL) |
Mild neutropenia | 1,000 to 1,500 microL |
Moderate neutropenia | 500 to 1,000 microL |
Severe neutropenia | Less than 500 microL |
The lower the count, the higher the risk. Having too few neutrophils can put you at risk of getting infections, and these infections may even be life-threatening without emergency medical attention [1]. In other cases, autoimmune neutropenia may cause only mild infections or no symptoms at all (asymptomatic) [1].
How common is autoimmune neutropenia, and who does it affect?
Primary autoimmune neutropenia is rare, occurring in about 1 out of 100,000 children under 10 [1]. It's diagnosed on average around 8 months old [1].
Secondary autoimmune neutropenia is often due to another autoimmune disease, like lupus or rheumatoid arthritis [1]. Most children with secondary AIN are diagnosed around age 10 (on average), and most adults diagnosed with secondary AIN are between the ages of 40 and 60 [1].
What are the symptoms of autoimmune neutropenia?
Autoimmune neutropenia doesn't always cause noticeable symptoms, but some people notice signs of infection, most commonly ear or respiratory infections [1]. Or, you may notice signs of an infection, including:
Ear infections (most common)
Respiratory infections (most common)
Mouth infections (ulcers, gingivitis)
Skin infections
Pneumonia
Meningitis
Urinary tract infections (UTIs)
Sepsis
There's an important pattern here: infections associated with primary AIN are usually mild. More serious infections, like pneumonia, meningitis, and sepsis, are more commonly associated with secondary AIN than primary AIN [1].
What causes autoimmune neutropenia?
AIN is classified as primary or secondary based on what's causing the low neutrophil levels.
What causes primary autoimmune neutropenia?
With primary AIN, antibodies target and destroy neutrophils. Antibodies are proteins in your immune system that destroy harmful bodily invaders, like viruses and bacteria. Researchers aren't sure what causes your body's antibodies to attack neutrophils [1].
What causes secondary autoimmune neutropenia?
The low neutrophil count associated with secondary AIN results from another cause or condition that prompts your immune system to destroy neutrophils [1].
Cause category | Examples |
Autoimmune diseases | Rheumatoid arthritis, lupus, autoimmune hemolytic anemia |
Cancer | Large granular lymphocyte leukemia |
Infections | HIV, parvovirus, hepatitis B |
Tumors | Wilms tumor, Hodgkin's disease |
Neurological diseases | Multiple sclerosis |
Transplants | Kidney or bone marrow transplants |
Medications | Including specific chemotherapy drugs |
How is autoimmune neutropenia diagnosed?
Your healthcare provider may notice your low neutrophil levels during blood work done to investigate potential causes of an infection or a fever [1]. Diagnosing AIN can be tricky since it has multiple causes. Your provider may arrive at a diagnosis after ruling out other conditions that may be causing your low neutrophil levels [1] [4].
Your healthcare provider may perform the following tests to diagnose or monitor autoimmune neutropenia.
Test | What it checks |
Complete blood count (CBC) | Counts neutrophils in your blood; levels can shift, so more than one CBC is usually needed to confirm consistently low levels; frequent CBCs show whether AIN is chronic |
Peripheral smear | Looking at blood under a microscope to assess neutrophil morphology (shape and appearance) |
Vitamin B12, folate, and copper tests | Reveal deficiencies associated with neutropenia; your body needs these to make neutrophils |
Liver function tests | Evaluate liver function and screen for viral hepatitis |
HIV and other viral studies | Viral infections may cause low white counts; may be part of the initial workup |
Flow cytometry | A lab test examining cells for signs of disease; may determine if an autoimmune condition is causing your neutropenia |
Imaging (MRI or CT scan) | Used if lymphoma is suspected as the cause |
Bone marrow aspiration and biopsy | Removes a small sample of bone marrow to test for disease; can show if neutropenia is related to blood cancer like leukemia |
Your provider may also order a blood test to check for signs of antibodies attacking your neutrophils. The most common tests are:
Indirect granulocyte immunofluorescence test (I-GIFT)
Granulocyte agglutination test (GAT)
Unfortunately, these antibody tests aren't always reliable for diagnosing AIN. Depending on what's causing your neutropenia and the timing of your test, they may not detect the antibodies, or they may produce false-positive results [1] [2]. A false-positive means the test detected antibodies when they aren't present. Your provider may order additional tests if they suspect a specific condition is causing your neutropenia.
How is autoimmune neutropenia treated?
Treatment depends on how severe your condition is [1].
For instance, asymptomatic infants with neutropenia may need more frequent CBCs to monitor their neutrophil levels, but they may not need immediate treatments [1]. Your provider may prescribe prophylactic antibiotics if your child is getting frequent infections [1]. While regular antibiotics treat infections, prophylactic antibiotics prevent them.
With secondary AIN, your provider will treat the underlying condition causing your low neutrophil count to prevent infections [1] [3]. They may also prescribe:
Treatment | How it helps |
G-CSF (granulocyte colony-stimulating factor) | The primary treatment for more severe neutropenia; spurs your body to make more neutrophils; can also prevent frequent infections associated with primary AIN |
Corticosteroids (like prednisone) | Limit your body's immune response so antibodies don't attack your neutrophils |
IVIG, rituximab, alemtuzumab | Additional agents used for those critically ill with severe autoimmune neutropenia |
Treating the underlying condition | For secondary AIN, addressing the root cause prevents infections |
What can I expect if I have autoimmune neutropenia?
Primary autoimmune neutropenia usually resolves on its own. In approximately 95% of children with AIN, neutrophil counts return to normal by ages two or three [1]. Almost all cases of primary AIN resolve by age 11 [1].
Otherwise, your prognosis depends on multiple factors, like what underlying condition may be causing your neutropenia. Treating the underlying disease and preventing infections can help boost your neutrophils to their normal levels [1].
Can autoimmune neutropenia be prevented?
Neither primary nor secondary autoimmune neutropenia is preventable [1]. Still, you can prevent complications by taking precautions to avoid infections [1].
When should I seek care?
See your provider immediately if you have a severe form of autoimmune neutropenia and develop a fever [1]. Sometimes, your provider may prescribe an antibiotic for you to have on hand in case you develop a fever. You'll likely receive treatment in a hospital [1].
Your provider can discuss symptoms you should be aware of and actions you should take to prevent complications if you have a severe, chronic form of autoimmune neutropenia.
Work with your healthcare provider to determine what an AIN diagnosis means for you or your child. Although symptoms and causes vary, the good news is that treatments like G-CSF are very effective at boosting neutrophil levels [1]. If your child has AIN, follow your provider's guidance on how frequently they'll need blood tests. Be on the lookout for signs of infection and get treatment as soon as possible to prevent possible complications.
Conclusion
When your defenders become the target. Autoimmune neutropenia puts your body in an uncomfortable position: the very immune system built to protect you ends up destroying its own first responders. Neutrophils, the white blood cells that hunt down bacteria and fungi, become the target of your body's antibodies, and your infection-fighting supply drops as a result.
The good news is that this condition is far more manageable than it sounds. Primary AIN, which mainly affects infants and toddlers, resolves on its own in about 95% of cases by ages two or three, and nearly all cases clear by age 11 [1]. For secondary AIN and more severe forms, treatments like G-CSF are very effective at boosting neutrophil levels back to normal [1], and corticosteroids, prophylactic antibiotics, and in rare severe cases agents like IVIG or rituximab round out the options [1].
What matters most is vigilance: watch for signs of infection, keep up with blood tests as your provider advises, and act quickly when a fever shows up. Work closely with your healthcare provider, and give your body the support it needs to rebuild its defenses. Explore Rinnit.com's library of blood disorder and autoimmune condition guides for more plain-language answers.
Frequently Asked Questions
What is autoimmune neutropenia? Autoimmune neutropenia (AIN) is a blood disorder where your immune system attacks your neutrophils, the white blood cells that destroy infection-causing invaders like fungi and bacteria, leaving you with a lower-than-normal neutrophil count.
Is autoimmune neutropenia the same as neutropenia? AIN is just one type of neutropenia. Neutropenia means your neutrophil count is below normal and is classified as mild (1,000 to 1,500 neutrophils per microL), moderate (500 to 1,000), or severe (less than 500). AIN is the version caused by an autoimmune attack.
What are the two types of autoimmune neutropenia? Primary AIN mainly affects infants and toddlers and isn't caused by another condition. It usually resolves on its own within a few years. Secondary AIN results from another condition (autoimmune diseases, infections, cancers, medications, etc.), mostly affects older children and adults, and is usually chronic.
Who gets primary autoimmune neutropenia? Primary autoimmune neutropenia primarily affects infants and young children. On average, it's diagnosed around 8 months old, and it's rare, occurring in about 1 in 100,000 children under 10.
Who gets secondary autoimmune neutropenia? Most children with secondary AIN are diagnosed around age 10 on average, and most adults are diagnosed between ages 40 and 60. It's often tied to autoimmune diseases like lupus or rheumatoid arthritis.
What are the symptoms of autoimmune neutropenia? Autoimmune neutropenia doesn't always cause noticeable symptoms. When it does, signs include infections: ear infections and respiratory infections (most common), mouth ulcers and gingivitis, skin infections, pneumonia, meningitis, UTIs, and sepsis. Primary AIN infections are usually mild; serious infections like pneumonia, meningitis, and sepsis are more common with secondary AIN.
What causes primary autoimmune neutropenia? Antibodies, proteins that normally destroy invaders like viruses and bacteria, mistakenly target and destroy neutrophils. Researchers aren't sure what causes this attack.
What causes secondary autoimmune neutropenia? Another condition prompts the immune system to destroy neutrophils, including autoimmune diseases (rheumatoid arthritis, lupus, autoimmune hemolytic anemia), cancer (large granular lymphocyte leukemia), infections (HIV, parvovirus, hepatitis B), tumors (Wilms tumor, Hodgkin's disease), neurological diseases (multiple sclerosis), kidney or bone marrow transplants, and medications including specific chemotherapy drugs.
How is autoimmune neutropenia diagnosed? Through blood work, usually a complete blood count (CBC), repeated to confirm consistently low neutrophil levels. Additional tests may include a peripheral smear, vitamin B12/folate/copper tests, liver function tests, HIV and viral studies, flow cytometry, imaging (MRI or CT), and bone marrow aspiration/biopsy. Antibody tests (I-GIFT and GAT) exist but aren't always reliable and can produce false positives.
How is autoimmune neutropenia treated? Mild, asymptomatic cases may only need frequent CBC monitoring. Treatments include prophylactic (preventive) antibiotics, G-CSF to spur neutrophil production, corticosteroids like prednisone to calm the immune attack, and treating the underlying condition in secondary AIN. For critically ill patients with severe AIN, IVIG, rituximab, and alemtuzumab may be used.
Will my child outgrow autoimmune neutropenia? In about 95% of children with primary AIN, neutrophil counts return to normal by ages two or three, and almost all cases resolve by age 11.
Is autoimmune neutropenia preventable? Neither primary nor secondary AIN is preventable. But you can prevent complications by taking precautions to avoid infections.
When should I seek care for autoimmune neutropenia? See your provider immediately if you have a severe form of AIN and develop a fever. You may be prescribed an antibiotic to keep on hand, and you'll likely receive treatment in a hospital.
How serious is autoimmune neutropenia? Autoimmune neutropenia ranges from having no symptoms at all to life-threatening infections. Having too few neutrophils raises your infection risk, and severe infections can be dangerous without emergency medical attention, but treatments like G-CSF are very effective at boosting neutrophil levels.
What questions should I ask my healthcare provider? Ask what's causing your low neutrophil count, how often you'll need blood tests, whether you should keep a fever antibiotic on hand, what signs of infection to watch for, and whether G-CSF or other treatments are right for you.
Related Reading
Lupus: Symptoms, Causes & Treatment Guide - One of the conditions that can cause secondary AIN.
References
Cleveland Clinic. Autoimmune Neutropenia. Cleveland Clinic. Last updated July 18, 2022. https://my.clevelandclinic.org/health/diseases/23475-autoimmune-neutropenia
Farruggia P, et al. Diagnosis and management of primary autoimmune neutropenia in children: insights for clinicians. Ther Adv Hematol. 2015;6(1):15-24. PMID 25642312. https://doi.org/10.1177/2040620714556642
Palmblad J, et al. How we diagnose and treat neutropenia in adults. Expert Rev Hematol. 2016;9(5):479-87. PMID 26778239. https://doi.org/10.1586/17474086.2016.1142867
Jinca C, et al. Primary autoimmune neutropenia of infancy and childhood in a cohort of patients from western Romania. Exp Ther Med. 2021;21(3):280. PMID 33603887. https://doi.org/10.3892/etm.2021.9711
De Filippo K, et al. The Secretive Life of Neutrophils Revealed by Intravital Microscopy. Front Cell Dev Biol. 2020;8:603230. PMID 33240898. https://doi.org/10.3389/fcell.2020.603230
Medical Disclaimer
This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read here.
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