1. Ask students to recall what they have previously discussed
about immunity, specifically innate immunity.
Explain that today you will be addressing another aspect
of the immune system: specific immunity. Students will
be enacting some of the processes that occur when a pathogen
enters the body and how the immune system reacts. Direct
students to pay careful attention not only to the role
they take on in this enactment, but also how their role
interacts with others.
3. One group of eight students will be given a box of
25 different color balloons
This group of students will stand in the hall until
the activity begins, and should be given an index card
that indicates that they will be acting as pathogens.
When they are asked to enter the room, they will pick
up a balloon and will be analogous to a pathogen entering
the body. The pathogen entering the body indicates
that it was able get past the body’s first line
Each index card will also indicate which color square
(antibody) can stick to each color balloon (pathogen).
If the sticker (antibody) is specific for the balloon
(pathogen), then it sticks to the pathogen and the
person who attached the antibody will sit down. If
it is not specific for that pathogen, then the person
holding the pathogen says: “I am a pathogen”,
which will indicate to the antibody that it cannot
bind to it.
When the antibody does not bind to the pathogen, then
the toothpick (cytotoxic T) cell can pop (kill) the balloon
(pathogen) as long as it is specific for that pathogen
(the pathogen will indicate whether it is specific by
saying nothing, or is not specific by say: “I am
Another group of eight students will each be provided
with an index card of instructions and a sheet of double
sided adhesive square stickers, 5 green, 5 blue, 5
purple, and 5 yellow (antibodies). If an antibody binds
to a pathogen, then it sticks to it and stays in its’ location.
The person holding the balloon sets it down on the
floor and this person returns to the hall and continues
to bring in pathogens. The person who stuck the antibody
to the balloon also returns to their group. Every time
an antibody binds, the double-sided adhesive square
will stick to the previously bound pathogen.
Another group of two students will each be provided
with three large garbage bags, which will represent
a phagocyte. As soon as three pathogens have been tagged
by an antibody and stuck together, then the phagocyte
can place the mass of antibody bound pathogens in the
bag and seal it.
8. The last group of six students will be provided with
eight toothpicks, which will simulate the cytotoxic T
cells. Each student will receive one red, blue, green,
and yellow toothpick. These cells can attempt an attack
on any pathogen that is not tagged by an antibody, however,
they must wait for the pathogen to say nothing, then
they can attack and pop (kill) the balloon, or say: “I
am a pathogen”, which means that this cytotoxic
cell is not specific to this pathogen and return to their
9. Each student in a group will be given an index card
specific to their identity.
10. Make students carefully read their instruction cards.
Pathogen Index Card:
|Antibody Index Card:
are an Antibody! You
are a protein that helps the body destroy pathogens
(foreign invaders). You are involved in a type
of immunity called humoral immunity. The body
in this activity is the classroom and your
job is to defend it to the best of your ability.
Each member of the group was given a sheet
of double sided adhesive square stickers: 5
green, 5 blue, 5 purple, and 5 yellow (antibodies).
The challenge for your group is to try to determine
which color antibody binds to each of the different
colored balloons (pathogens). Initially this will
be trial and error, however, as the activity proceeds
you should be able to determine which antibodies
can bind to each color balloon. The activity will
proceed in a specific order, meaning that the antibody
in this group with the number 1 in the lower right
hand corner will go first. As each pathogen enters
the room, one person from the group will act as
an antibody and attempt to bind to the pathogen
which colored square they believe will be most
effective. If the pathogen says nothing after confronting
it within ten seconds, then place the adhesive
square you selected on the balloon. If the pathogen
says: “I am a pathogen”, this indicates
that this antibody you selected cannot bind to
this particular pathogen. After you have placed
the sticker on the balloon or have been informed
that you are not specific for that pathogen, please
return to your seat. However, if your sticker does
bind and there is a balloon(s) on the floor that
also has an antibody bound, then stick the two
balloons together and then sit down (leave the
balloons on the floor). Good Luck!
|Macrophage Index Card:
are a Macrophage! You
are a white blood cell that engulfs or digests
pathogens (foreign invaders) in the body.
You are involved in a type of immunity called
humoral immunity. The body in this activity
is the classroom and your job is to defend
it to the best of your ability. Each group
member was given 3 large garbage bags (macrophages).
You are responsible for engulfing masses
of pathogens (balloons) that have antibodies
(square, colored stickers) bound to them.
When there is a mass of three antibody-bound
pathogens, you can take one of the bags and
place the mass inside of it and return to
your group with this bag. Good Luck!
|Cytotoxic T Cell Index Card:
are a Cytotoxic T Cell! You
are a type of white blood cell that attacks
pathogens (foreign invaders) directly by transferring
proteins into the cell membrane of the pathogen
and causing fluid from inside the cell to leak
out of the membrane. You are involved in a
type of immunity called cell-mediated immunity.
The body in this activity is the classroom
and your job is to defend it to the best of
your ability. You have the ability to attack
the pathogen directly and in this activity
you will try to attack any pathogens that make
it past the humoral response (antibodies) by
confronting the pathogen. When you confront
the pathogen you have a choice of using a red,
blue, yellow, or green toothpick. The pathogen
will say: “My antigens are what ever
color the balloon is”, which will indicate
that you may attack the pathogen by popping
(killing) the balloon (pathogen) with the toothpick;
or they may respond by saying: “I am
a pathogen”, which means that particular
colored toothpick (Cytotoxic T cell) cannot
kill this pathogen). Group members must confront
the pathogens individually and only once per
round, meaning that if one group member attacked
the pathogen and could not kill it, then that
pathogen survived the round. Students must
also proceed in the correct order, by referring
to the number on your index card in the lower
right-hand corner. Good Luck!
11. Once students have enacted this several times bring
the group back for a discussion. The focus of the
discussion should center on developing an understanding
for adaptive immunity and recognizing how antigenic
specificity, diversity, immunologic memory, and self/non-self
recognition relate to this type of response. The
discussion should also develop some of the components
that were left out of this activity that are critical
to cell-mediated immunity. Helper T cells identify
antigens present on pathogens and turn on or initiate
the release of cytotoxic T cells that are specific
to this type of antigen. Suppressor T cells suppress
the release of cytotoxic T cells once the pathogen
has been destroyed. It is also important for the
students to understand that phagocytes are capable
of engulfing pathogens before they have infected
a cell, however, once this infection has occurred,
the system can utilize antibodies, cytotoxic T cells,
or macrophages. Antibodies are capable of binding
to pathogens and forming large masses of antibody
bound pathogens that can be engulfed later by macrophages.
Cytotoxic T cells can kill pathogens directly; however,
they must be specific to that particular pathogen
and its antigens. This aforementioned activity is
regulated by helper and suppresser T cells.
12. Have students individually diagram the actions and
interactions of this aspect of the immune system.
13. While students have been introduced to the idea of
specificity, they have not addressed how this specificity
occurs; this maybe an extension for students ready to
14. In closure, review and explore the interconnections
between pathogens, antigens, antibodies, lymphocytes,
humoral immunity, and cell-mediated immunity.
Remind students that the Public Health Reflection I
Homework sheet is to be turned in at the start of class
before beginning the “Waterborne Diseases” lesson.
Students can be pre-assessed with the initial question.
2. Within a class discussion students can be assessed on
their ability to describe how antigenic specificity allows
the immune system to distinguish subtle differences among
3. Within a class discussion students can be assessed on
their ability to explain how an immunologic memory can
induce a heightened state of immune reactivity.
4. A graphic and the class discussion can allow for assessment
of ability to describe the functional cells of the immune
system and articulate how these cells distinguish between
self and non-self cells.