We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is the Membrane Attack Complex?

Daniel Liden
By
Updated May 16, 2024
Our promise to you
WiseGEEK is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGEEK, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The membrane attack complex (MAC), frequently referred to as the complement membrane attack complex, is one of the methods used by the immune system to attack threats to the body. It is closely related to the complement system, which exists to aid antibodies and other aspects of the immune system in clearing pathogens from a person's body. The complementary system and the attack complex both involve many varieties of proteins that are found in the blood. The proteins bind to the membranes of pathogenic cells and form a circular pore that allows extracellular substances into the cell. When enough of these pores form, the integrity of the cell is severely compromised and cellular death is almost inevitable.

There are two primary stages through which the different proteins in the membrane attack complex act to destroy pathogenic cells. The first stage, usually referred to as initiation, involves the proteins C5, C6, and C7. Through a procedure involving the cleaving and binding of these proteins, the C7 protein is able to penetrate the pathogenic cell's membrane. Proteins C6 and C5 are bound to protein C7; this initiation stage and insertion into the membrane are necessary for the attack complex to proceed.

The second stage is referred to as the polymerization stage, which involves the proteins C8 and C9 and has the goal of actually forming the pore that will eventually destroy the pathogenic cell. C8 is able to insert itself into the pathogenic cell's membrane because of traits relating to the polarity of the molecules that make up the membrane and the protein. It is then able to induce many C9 proteins to form into a porous structure that penetrates the pathogenic cell's membrane. The structure is connected to the C5, C6, C7, and C8 proteins.

In any immune system response, it is important that the immune system be able to distinguish the body's cells from foreign cells so that it only targets pathogenic cells. This is also true in the membrane attack complex. The protein CD59, also referred to as protectin, is present on normal non-pathogenic cells; it prevents the process from acting on these healthy cells. Many viruses, such as HIV, are able to incorporate parts of host cells, including CD59, into their own viral forms, so they are unaffected.

WiseGEEK is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Daniel Liden
By Daniel Liden , Former Writer
Daniel Liden, a talented writer with a passion for cutting-edge topics and data analysis, brings a unique perspective to his work. With a diverse academic background, he crafts compelling content on complex subjects, showcasing his ability to effectively communicate intricate ideas. He is skilled at understanding and connecting with target audiences, making him a valuable contributor.

Discussion Comments

By nony — On Nov 11, 2011

@SkyWhisperer - Yes, in a properly working immune system both the membrane attack complex and the antibody complement work together to rid the body of pathogens.

I believe that’s why it’s so important to have a strong immune system. Certain foods, like just about anything with sugar, will weaken your immune system. As a result, you will have a greater propensity towards getting sick, or it will take you longer to get well.

Foods that will strengthen your immune system, by contrast, include fruits and vegetables which should be the staple in just about any diet. I always make sure I get a serving each day, in addition to my daily dietary supplements.

I’ve had some years where I didn’t get a cold all winter season. Of course I realize skeptics will call that “anecdotal” evidence, but when it’s my story that is the anecdote, that’s all I need.

By SkyWhisperer — On Nov 11, 2011

This is a great piece. I finally understand why a body’s immune system cannot break down HIV AIDS. The AIDS virus makes itself indistinguishable from regular cells, in a nutshell, so that the membrane attack complex cannot tell the difference.

Accordingly, the virus is left untargeted. Of course I have heard of people being helped who do have HIV. I don’t know how that works, but knowing where the problem is gives you the first clue so that you can start working on a solution.

Prior to reading this article, the only thing I had heard about AIDS was that the immune system couldn’t deal with it, but I didn’t know how.

Daniel Liden

Daniel Liden

Former Writer

Daniel Liden, a talented writer with a passion for cutting-edge topics and data analysis, brings a unique perspective to...
Learn more
WiseGEEK, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGEEK, in your inbox

Our latest articles, guides, and more, delivered daily.