This antibody doesn't kill bacteria, it just neutralises their toxins

Scientists find our largest antibody doesn't destroy bacteria but blocks their toxins by stiffening them - a discovery that could inspire gentler, next-gen therapies for tough infections

Our immune system is constantly at war, fighting off invading bacteria and their dangerous toxins. Now, scientists have uncovered a new weapon in this battle: the body’s largest antibody, IgM (Immunoglobulin M).

 

A recent study shared by the Ministry of Science and Technology of the Government of India shows that IgM does more than just bind to microbes. It acts like a mechanical brace, stiffening bacterial toxins and preventing them from causing harm.

 

This discovery, according to the ministry, could inspire new therapies by designing antibodies that mechanically disarm dangerous proteins.

 

According to the study titled Unraveling antibody-induced mechanical stability of antigen: Insights from single-molecule studies, published in Protein Science (Wiley Online Library), IgM is the body’s largest antibody. 

 

What did the researchers test?

The study, led by scientists from Ashoka University, Sonipat, looked at Protein L, a molecule from the bacterium Finegoldia magna. Protein L can latch onto antibodies in unusual ways and interfere with normal immune responses. Using a high-precision method called single-molecule force spectroscopy, the team pulled on single molecules to see how strong or fragile they were. With IgM bound, Protein L became much harder to unfold. 

Why does IgM make toxins 'stiffer'?

IgM is large and has many binding sites. It can hold a toxin at several spots at once, like using multiple hands, so the protein resists force and doesn’t fall apart into harmful shapes. The effect got stronger as more IgM was present. Smaller antibodies didn’t show the same stabilising power.

Why is this important for health?

Inside our bodies, bacteria and their toxins face mechanical forces such as blood flow and immune cell attacks. If IgM can mechanically neutralise toxins by stiffening them, we could design new antibody therapies that disarm dangerous proteins without necessarily killing the bacteria outright—another tool against infections and resistance. 

How does this change what we thought about antibodies?

We usually picture antibodies as “chemical keys” fitting “microbial locks.” According to the ministry, this work adds a new role: mechanical modulators. Antibodies can change a protein’s physical properties to make it safer. That’s a big idea that could inspire new therapies. 

How can this help develop new treatments?

The ministry said if we can design antibodies that intentionally stiffen harmful proteins, we might block toxins before they damage cells. This approach could complement antibiotics and help in tough-to-treat infections. More tests in cells and animals would be the next steps.

 

The ministry said that the discovery of IgM’s mechanical power marks a shift in how we understand immunity and could guide the design of next-generation antibody therapies.

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This content is for informational purposes only and is not a substitute for professional medical advice.