--- title: "Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) | Microbiology" description: "Antibody-dependent cell-mediated cytotoxicity (ADCC) is an antibody-triggered killing process where NK cells destroy coated targets in Microbiology." canonical: "https://fiveable.me/microbio/key-terms/antibody-dependent-cell-mediated-cytotoxicity-adcc" type: "key-term" subject: "Microbiology" unit: "Unit 18" --- # Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) | Microbiology ## Definition Antibody-dependent cell-mediated cytotoxicity (ADCC) is an immune response in Microbiology where antibodies coat a target cell and immune effector cells, especially NK cells, bind the antibody Fc region and kill the target. ## What It Is Antibody-dependent cell-mediated cytotoxicity, or ADCC, is a way the immune system destroys cells after antibodies have already marked them. In Microbiology, you usually see it as part of the adaptive immune response working with innate effector cells like natural killer (NK) cells, macrophages, and neutrophils. The basic idea is simple: an antibody binds to an antigen on the surface of a target cell, and then an immune cell recognizes the exposed Fc region of that antibody. The Fc region is the stem of the antibody, the part that does the signaling work after the antibody has attached to the target. Effector cells have Fc receptors, especially Fcγ receptors for IgG, that latch onto that Fc region. Once several Fc receptors are engaged, the effector cell gets a strong activation signal. NK cells respond by releasing cytotoxic molecules such as perforin and granzymes, which damage the target cell and push it toward apoptosis. Macrophages and neutrophils can also contribute by releasing toxic substances or engulfing damaged cells, depending on the situation. ADCC is different from simple neutralization. Neutralization blocks a pathogen from entering cells, while ADCC is a more direct kill step after the target has been tagged. It is also different from complement-driven lysis, because ADCC uses cells, not the complement cascade, to finish the job. You can think of ADCC as a two-step system: antibodies identify the target, then immune cells act as the execution crew. That makes it especially useful against virus-infected cells and some tumor cells, where the immune system needs to remove host cells that are behaving abnormally. In lab diagrams or exam questions, the clue is usually a cell coated in IgG with an NK cell binding through an Fc receptor and releasing cytotoxic granules. ## Why It Matters ADCC shows up in Microbiology because it connects adaptive specificity with innate killing power. B cells make the antibodies, but the actual destruction can be carried out by NK cells or other effector cells. That crossover is a common theme in immunity, and it explains why antibodies do more than just stick to microbes. This term also helps you separate several antibody-based mechanisms that are easy to mix up. If a question describes antibody-coated targets plus NK cell recognition through Fc receptors, you are looking at ADCC. If the prompt focuses on coating a pathogen so it is easier to eat, that is opsonization. If it focuses on antigen-antibody complexes causing inflammation in tissues, that points more toward immune complex reactions. Microbiology classes often use ADCC to show how the immune system handles infected body cells, not just free-floating microbes. Viruses are a great example because once a cell is infected, antibodies alone cannot reach the virus hidden inside the cell. ADCC gives the immune system a way to flag and eliminate that infected cell before it keeps producing more virus. The term also matters in treatment contexts. Therapeutic antibodies used in some cancers can recruit NK cells through ADCC, which means the antibody does more than just bind the tumor. It turns the patient’s own effector cells into a targeted killing system. ## Connections ### opsonization Opsonization is the tagging step that makes a target easier for immune cells to recognize and remove. ADCC also depends on antibody coating, but the outcome is different: instead of mainly promoting phagocytosis, the antibody tag activates an effector cell to kill the target. If a question describes a coated cell being attacked by NK cells, think ADCC rather than simple opsonization. ### natural killer (NK) cell NK cells are the best-known effector cells in ADCC because they can bind IgG-coated targets through Fc receptors and release perforin and granzymes. They bridge innate and adaptive immunity by using antibody signals to focus their killing. When a diagram shows a lymphocyte attaching to a coated cell and causing apoptosis, NK cells are usually the cell type being described. ### Fc receptor Fc receptors are the receptors on immune cells that recognize the Fc portion of antibodies. In ADCC, they are the connection point between the antibody on the target and the effector cell doing the killing. Without Fc receptor binding, the antibody can still bind antigen, but the ADCC response does not get triggered. ### [Antibody-Dependent Cell-Mediated Cytotoxicity](/microbio/key-terms/antibody-dependent-cell-mediated-cytotoxicity) This term is sometimes written out in full, but it refers to the same process as ADCC. You may see either version in Microbiology notes, figure labels, or quiz questions. If the long form appears in a sentence about NK cells, Fcγ receptors, and IgG-coated targets, it is describing the same mechanism. ## On the AP Exam A quiz item or diagram question may show an antibody-coated target cell and ask you to identify the immune mechanism. The move is to trace the sequence: IgG binds the target, Fcγ receptors on an NK cell bind the Fc region, and the effector cell releases cytotoxic molecules to kill the target. If the question includes virus-infected cells or tumor cells, ADCC is a strong fit. On short-answer prompts, you might compare ADCC with opsonization or neutralization, or explain why antibodies can help remove cells that are already infected. In lab or image-based questions, look for a coated target cell, an effector cell with Fc receptors, and signs of apoptosis or membrane damage. The safest answer uses the vocabulary of antibody coating, Fc binding, and effector-cell killing. ## antibody-dependent cell-mediated cytotoxicity (ADCC) vs opsonization Both ADCC and opsonization involve antibodies coating a target cell, so they are easy to mix up. The difference is what happens next. In opsonization, the coating mainly makes the target easier for phagocytes to engulf. In ADCC, the antibody coating recruits an effector cell, especially an NK cell, to kill the target cell directly. ## Key Takeaways - ADCC is the killing of an antibody-coated target cell by an immune effector cell, usually through Fc receptor binding. - IgG is the main antibody class linked to ADCC because its Fc region binds well to Fcγ receptors on NK cells and other effector cells. - ADCC is a bridge between adaptive immunity and innate killing, since antibodies provide the specificity and effector cells provide the attack. - This mechanism is useful for removing virus-infected cells and some tumor cells that should not keep surviving. - When you see antibody-coated cells plus NK cells releasing cytotoxic molecules, you are probably looking at ADCC. ## FAQs ### What is antibody-dependent cell-mediated cytotoxicity (ADCC) in Microbiology? ADCC is an immune process where antibodies coat a target cell and then immune effector cells bind the antibody Fc region and kill the target. In Microbiology, it is a good example of adaptive immunity directing innate immune cells. NK cells are the classic effector cells, but macrophages and neutrophils can also contribute. ### How is ADCC different from opsonization? Both involve antibodies attached to a target, but they lead to different outcomes. Opsonization mainly makes a target easier to phagocytose, while ADCC activates an effector cell to kill the target, often through cytotoxic granule release. If an NK cell is involved, ADCC is the better match. ### Which immune cells carry out ADCC? NK cells are the main ADCC cells you will see in Microbiology. Macrophages and neutrophils can also participate because they have Fc receptors and can respond to antibody-tagged targets. The exact cell depends on the target and the immune context. ### Why does ADCC matter for viruses and cancer? Viruses hide inside infected host cells, so antibodies cannot just neutralize every problem on their own. ADCC lets the immune system identify those infected cells and destroy them. The same idea is used in some cancer therapies, where antibodies help direct immune cells toward tumor cells. ## Related Study Guides - [18.1 Overview of Specific Adaptive Immunity](/microbio/unit-18/1-overview-specific-adaptive-immunity/study-guide/CKmHguOY1EWmJIKh) - [19.1 Hypersensitivities](/microbio/unit-19/1-hypersensitivities/study-guide/m1rInCFdYz2PwE8P) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`) ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/microbio/key-terms/antibody-dependent-cell-mediated-cytotoxicity-adcc#resource","name":"Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) | Microbiology","url":"https://fiveable.me/microbio/key-terms/antibody-dependent-cell-mediated-cytotoxicity-adcc","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/microbio/key-terms/antibody-dependent-cell-mediated-cytotoxicity-adcc#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:23:45.862Z","isPartOf":{"@type":"Collection","name":"Microbiology Key Terms","url":"https://fiveable.me/microbio/key-terms"},"author":{"@type":"Organization","@id":"https://fiveable.me/editorial#content-team","name":"Fiveable Content Team","url":"https://fiveable.me/editorial","parentOrganization":{"@id":"https://fiveable.me/#organization"},"member":[{"@type":"Person","name":"Amanda DoAmaral","sameAs":["https://www.linkedin.com/in/adoamaral"]},{"@type":"Person","name":"Becky Bahr","sameAs":["https://www.linkedin.com/in/becky-bahr-b52743132"]}]},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/microbio/key-terms/antibody-dependent-cell-mediated-cytotoxicity-adcc#term","name":"antibody-dependent cell-mediated cytotoxicity (ADCC)","description":"Antibody-dependent cell-mediated cytotoxicity (ADCC) is an immune response in Microbiology where antibodies coat a target cell and immune effector cells, especially NK cells, bind the antibody Fc region and kill the target.","url":"https://fiveable.me/microbio/key-terms/antibody-dependent-cell-mediated-cytotoxicity-adcc","inDefinedTermSet":{"@type":"DefinedTermSet","name":"Microbiology Key Terms","url":"https://fiveable.me/microbio/key-terms"}},{"@type":"FAQPage","mainEntity":[{"@type":"Question","name":"What is antibody-dependent cell-mediated cytotoxicity (ADCC) in Microbiology?","acceptedAnswer":{"@type":"Answer","text":"ADCC is an immune process where antibodies coat a target cell and then immune effector cells bind the antibody Fc region and kill the target. In Microbiology, it is a good example of adaptive immunity directing innate immune cells. NK cells are the classic effector cells, but macrophages and neutrophils can also contribute."}},{"@type":"Question","name":"How is ADCC different from opsonization?","acceptedAnswer":{"@type":"Answer","text":"Both involve antibodies attached to a target, but they lead to different outcomes. Opsonization mainly makes a target easier to phagocytose, while ADCC activates an effector cell to kill the target, often through cytotoxic granule release. If an NK cell is involved, ADCC is the better match."}},{"@type":"Question","name":"Which immune cells carry out ADCC?","acceptedAnswer":{"@type":"Answer","text":"NK cells are the main ADCC cells you will see in Microbiology. Macrophages and neutrophils can also participate because they have Fc receptors and can respond to antibody-tagged targets. The exact cell depends on the target and the immune context."}},{"@type":"Question","name":"Why does ADCC matter for viruses and cancer?","acceptedAnswer":{"@type":"Answer","text":"Viruses hide inside infected host cells, so antibodies cannot just neutralize every problem on their own. ADCC lets the immune system identify those infected cells and destroy them. The same idea is used in some cancer therapies, where antibodies help direct immune cells toward tumor cells."}}]},{"@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Microbiology","item":"https://fiveable.me/microbio"},{"@type":"ListItem","position":2,"name":"Key Terms","item":"https://fiveable.me/microbio/key-terms"},{"@type":"ListItem","position":3,"name":"Unit 18","item":"https://fiveable.me/microbio/unit-18"},{"@type":"ListItem","position":4,"name":"antibody-dependent cell-mediated cytotoxicity (ADCC)"}]}]} ```