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Short summary: a classroom activity to introduce students to the basic principles of immunology, specifically antibodies, in both their biological role in immune defence and as research tools by using a hands-on activity to practice working scientifically. All the instructions on this webpage can also be downloaded as a word document.

Relevance to the Curriculum and Learning Goals:

  1. Working scientifically
    • Recording and presenting experimental data in tables and graphs
    • Making hypotheses/predictions based on prior knowledge and testing them
    • Interpreting observations, identifying patterns, and using collected data to draw conclusions
    • Strictly following protocols in detail to obtain reproducible results
    • Applying concepts learned to a different context


  1. Biology
    • Different cell types are adapted for their specific functions
    • Cell types differ in their cell surface proteome
    • The immune system is equipped to differentiate self from non-self to defend the body
    • Antibodies are a part of the immune system and (among other tasks) specifically bind to non-self antigens, marking cells carrying them for destruction
    • Antibody binding is bivalent and results in the formation of clumps (coagulation)
    • The immune system also plays a role in blood transfusions (and transplantations in general), particularly in the compatibility of blood groups (and the rejection of transplants)
    • Antibodies are used as tools in research beyond their biological function (general concept in research: adapting biological functionality as tools)

Materials needed:

Preparation needed:

  • Prepare laminated “test plate” sheets according to the number of students/pairs
  • Prepare “blood” and “antibody” solutions:
    • “Type A” blood: vinegar with red food dye
    • “Type B” blood: milk with red food dye (NB: too much may lead to coagulation – make sure milk is not clotting in the tube)
    • “Type O” blood: water with red food dye
    • “antibodies from A” : vinegar
    • “antibodies from B” : milk
  • Prepare one test kit for each student/pair:
    • one tube labelled “antibodies from A”
    • one tube labelled “antibodies from B”
    • one tube labelled “Type A blood”
    • one tube labelled “Type B blood”
    • one tube labelled “Type O blood
    • a marker pen (unless the students have one)
    • a couple of stirrers
    • three plastic droppers
  • Provide the worksheets, instructions, a laminated TEST PLATE sheet, and test kits to the students

Suggested Lesson Plan

  1. Animation to introduce antibodies and basic concepts of immunology (provided):

“In our body we have lots of different kinds of cells: brain cells in the brain and gut cells in the gut and red blood cells and white blood cells in the blood - and sometimes bacteria or other types of pathogens which can make us sick. Our immune system is armed to defend us against these kinds of pathogens, to find them and kill them. At the same time, the immune system must not attack the body’s own cells – because we need them. So how can our body distinguish between the cells that belong to itself and the cells that don’t belong to itself? Well, one of the ways cells are different from each other are the kinds of markers they have on their surface. Blood cells have one set of markers and brain cells have another set. And they all look slightly different from each other. Bacterial cells have different sets of cell surface markers compared to human cells. Sometimes even the cells from one person have different sets compared to another person. For example, the red blood cells of blood group A have different surface markers from those of blood group B. Scientists also call these surface markers “antigens”. Now, the immune system can detect these cell surface antigens with small proteins called antibodies. Antibodies are produced by special white blood cells called B cells and they can bind to the surface antigens of foreign cells but not the body’s own cells. Different antibodies have different shapes which match the different shapes of the antigens. In this way, antibodies are very specific, meaning that each antibody can only bind to one particular surface antigen – like a lock and a key. Because antibodies have two arms, they can bind to two antigens at the same time and as you can imagine lots of antibodies binding to lots of cells can make big clumps. These big clumps can then be found and eaten up by another important player of the immune system, the phagocytes. The B cells in our body produce lots and lots of different antibodies so that we can detect lots and lots of different kinds of cells that might enter our body from the outside. In this way, the immune system can fight almost anything that has different surface antigens compared to our own cells. At the same time, our body has mechanisms that make sure that we don’t have B cells that make antibodies against our own surface antigens so that we don’t attack ourselves. As you can see, antibodies are one of the most powerful tools the immune system has to defend our body against pathogens.”

  1. Introduction to the activity, leading on from basic immunological concepts to the specific example of antibodies in blood transfusion:

Today we are going to investigate how antibodies play a role in blood transfusions.

  • Opportunity to talk about blood and what it is for (transport of nutrients and oxygen) and about blood donations (losing a lot of blood is a big problem, so blood banks are important; do anyone’s parents donate blood?)
  • Introduce blood groups (who knows how many there are and what they are called?)
  • Using the top part of the “Blood Groups” slide, explain that the difference between blood groups is the kind of surface marker that is expressed on their surface – blood group A expresses one marker, blood group B expresses another marker, blood group AB expresses both and blood group O expresses none
  • Using the bottom half of the slide introduce the antibodies present and the concept that there are no antibodies against self (depending on level of class, this may make the answers to the worksheets used later on too obvious)
  1. Activity

Now let’s test our understanding with an experiment. Of course we cannot use real blood today but we are going to use coloured milk and vinegar solutions to represent blood. We will test what happens if you mix blood of one blood group with antibodies from another blood group to find out which blood groups are compatible. This experiment is a representation of the blood clotting test a nurse would do in a hospital to test your blood group. The correct term for the experiment is “agglutination assay”.

  1. Discussion and further information
  • Referring back to the animation, discuss observations and explanations:
    • Different blood groups have different surface antigens
    • We have antibodies against surface antigens that are not our own
    • Having antibodies against the donated blood can cause blood clotting for the same reason that bacteria form clumps
    • Blood clots can be life threatening when they clog arteries or even travel into the heart
  • Ask which blood groups are the most desirable to be (AB because it is the “universal acceptor” as it does not have any antibodies against either of the blood cell antigens since it expresses both of them on its own cells) and the most needed in blood banks (O because it is the “universal donor” as it does not express either of the antigens on its surface so it does not matter whether antibodies are present)
  • Based on everything they have learned today, ask students to fill in the BLOOD GROUPS worksheet

Powerpoint slides with the results to help you go through them with your class available here

  • Possibility to discuss Rhesus factors (excluded here for simplicity)
  • Possibility to discuss inheritance of blood groups (A and B are dominant, O is recessive)
  • Possibility to discuss role of antibodies in autoimmunity (e.g. systemic lupus erythematosus, some forms of coeliac disease, and some forms of arthritis)
  • Possibility to discuss the use of antibodies as tools in biomedical research using the video clip provided, leading on to the general concept of adapting biological activities as tools in and outside of science (biomimicry, CRISPR/Cas9, …)


This activity is based on but not identical with Arnold S. et al. (2012) The classroom-friendly ABO blood types kit: blood agglutination simulation. Journal of Biological Education, 46 (1), 45-51.

Credits also to openclipart users Moini, povke, and ozhank for the base for some of the images in the animation.

Risk Assessment


Using milk, vinegar, water and food dye to illustrate blood clotting and transfusion compatibility


  1. Slipping if solutions are spilled on the floor
  2. Getting milk or vinegar solutions into eyes or mouth
  3. Allergic reaction if lactose intolerant students ingest milk
  4. Poking stirrers into eyes

Action to be taken to minimise risks

  1. Take care not to spill solutions (store with lids closed) and promptly clean up any spills
  2. Advise students not to splash the solutions
  3. Advise students not to ingest solutions particularly if lactose intolerant
  4. Use stirrers with round edges (never use tooth picks!)

Action to be taken in the event of an accident

  1. Call first aider in event of injury
  2. Rinse eyes with water or eyewash
  3. Refer student to nurse or parents
  4. Call first aider in event of injury



This is a simulation experiment. Tubes contain water, milk, and vinegar. No blood or antibodies are used.

Aim: To test which blood groups are compatible and which coagulate (form clumps) when combined

  1. Lay out the laminated test plate on a flat surface.
  2. Label your plastic droppers A, B, and O.
  3. Using plastic dropper A, add a few drops of “antibodies from A” to the top row.
  4. Using plastic dropper B, add a few drops of “antibodies from B” to the bottom row.
  5. Using plastic dropper A add a few drops of “Type A blood” to the first column.
  6. Using plastic dropper B, add a few drops of “Type B blood” to the second column.
  7. Using plastic dropper A, add a few drops of “Type A blood” to the third column.
  8. Using plastic dropper B, add a few drops of “Type B blood” to the third column as well.
  9. Using plastic dropper  O, add a few drops of “Type O blood” to the fourth column.
  10. Mix with the stirrers.
  11. Record your observations in the table on the EXPERIMENTAL RESULTS worksheet and write down a hypothesis on how antibodies could cause the reactions you see.


Please record the results of the Blood Type Testing experiment in the table below. Carefully describe your observations and explain how antibodies can cause the reactions you see.


Blood Group

Antibdodies from




















Please fill in the table below using the data you collected in the Blood Type Testing experiment and the information from the video.


This activity was developed by Corinna Kulicke and Abigail Elliot, Cerundolo group, in the MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine