STEM Up: The Immune System

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Stem Up




Attack of the Holiday Pathogens

Read & Learn

How does your immune system keep you healthy?

The Science Communication Club

Volume 01 Issue 02

Meet the Team Diana Nelles // Director Diana is an undergraduate student specialising in pharmacology and toxicology at the University of Toronto. She hopes to spark a scientific interest and curiosity within the community by organizing interactive events and projects that promote STEM for all ages.

Hayley McKay // Writer Hayley is a graduate student studying plant molecular genetics at the University of Toronto. Outside of the lab, she writes exciting and informative stories about science in an effort to connect and engage more people in STEAM (Science, Technology, Engineering, Art & Math).

Melissa Wong // Writer Melissa is an undergraduate student studying pharmacology at the University of Toronto. She is excited about writing articles and organizing events that promote science communication within and outside the local community.

Shanling Lei // Illustrator Shanling is an undergraduate student studying life sciences at the University of Toronto. She communicates complex ideas in science through fun and creative illustrations.

Eugenia Yi // Illustrator Shanling is an undergraduate student at the University of Toronto’s Faculty of Arts and Sciences. She creates engaging and interactive illustrations for anyone interested in the sciences.

Amy Zhang // Layout Designer Amy is a digital illustrator pursuing her graduate studies in biomedical communication at the University of Toronto. She wants to create art that gets people excited about interacting with science.


Table of Contents 4 Santa Claus and the North Pole Gang 11 How Our Immune System Keeps Us Healthy 16 Allergic Reactions 20 Autoimmune Diseases: Celiac Disease 24 Crossword Puzzle 26 Word Search




Santa Claus & the North Pole Gang Keep the World Safe Written by Hayley Illustrated by Shanling


Oh no! The Grinch and his South Pole Elves (pathogens) have decided they want to ruin the holidays for the world by stealing the holiday spirit! But worry not, everyone at the North Pole (bone marrow/immune system) is not going to let that happen!

N e u t ro p h i l s

M o n o cy t e


E o si n o p hil

Nutcrackers (neutrophils) and Santa Claus (monocyte) arrive right away and flash freeze the South Pole Elves with the help of Frosty the Snowman (eosinophil). B as op h il Rudolf (basophil) hears the commotion and comes running, his shiny red nose a beacon to the world that something is amiss!


Around the world, holiday spirit is dwindling and snow is melting (inflammation/fever) because Santa and the Nutcrackers weren’t able to freeze all of the South Pole Elves, but never fear – Mrs. Claus (B-Cell), Santa’s Reindeer (T-Cells) and the North Pole Elves (antibodies) are here! T-Cells


A n ti b o di e s

A nt

i ge

n s

Before Santa and the Nutcrackers froze all the South Pole Elves, they noticed they had gingerbread cookies (antigens) in their pockets. Of course, being cookie lovers, Santa and the Nutcrackers gobbled up the gingerbread cookies. Since Santa and the Nutcrackers eat loads of cookies, they have developed the ability to decipher the recipe used to make a cookie with just one bite!

Back at the North Pole, Santa and the Nutcrackers show Mrs. Claus the gingerbread cookie recipe used by the South Pole Elves and she sets about making a big batch for all the North Pole Elves. 7

! Yum

After a quick snack, the North Pole Elves are able to remember these gingerbread cookies, the same ones Santa and the Nutcrackers took from the South Pole Elves. This cookie-remembering skill has already come in handy because look – more South Pole Elves are launching an attack to help the Grinch fight his grinchy battle! Attack!

t No

so fast!

The North Pole Elves recognize the South Pole Elves right away because of the cookies in their pockets, and head straight to Santa and the Nutcrackers to let them know. As soon as the North Pole Elves tell them, Santa and the Nutcrackers flash freeze the South Pole Elves before they have the chance to steal any more holiday cheer.

Meanwhile, the Grinch himself has snuck into a Christmas tree farm and is beginning to steal all the trees! All he wants is to make everyone sad so he is making sure no one can get a Christmas tree this year!




er But Santa’s Reindeer, who also got a taste of Mrs. Claus’ in yth ing will be m gingerbread cookies are on patrol. Of course, the Grinch sometimes gets hungry, so he carries a stash of the same gingerbread cookies as the South Pole Elves - he got the cookies from them after all.

But Santa’s Reindeer, with their strong noses sniff out the Grinch hiding in the Christmas tree farm from the cookies he’s got in his pocket. The Reindeer use their antlers and charge at the Grinch, taking down some Christmas trees with them. Even though some trees had to be sacrificed, the Reindeer heroically trap the Grinch in a cage of antlers, stopping him from stealing any more trees!

Take that!

All is well around the world again -

with the South Pole Elves frozen,


G r u m ble .. .

and the Grinch trapped by the Reindeer’s antlers,

the snow begins to fall and holiday spirit returns.

Even though the North Pole may only be mentioned around the holiday season, it’s always a bustle of activity keeping the world safe, and making toys for all the world’s children, of course! 9


How Our

Immune System Keeps Us Healthy Written by Hayley Illustrated by Shanling


he immune system is one of the most complicated but important systems in the human body. Without it, we wouldn’t be able to stay healthy! The immune system is made up of many different organs and specialized cells all working together to fight off infections from things like bacteria, viruses, parasites and other germs (or “pathogens”). Our immune systems also protect us against any of our own cells that are growing too much or aren’t working properly, otherwise they can turn into serious diseases like cancer.

All of the specialized immune cells are produced in our bone marrow - the squishy sponge-like centres of large bones like the femur. The lymphatic system makes up the organs involved in the immune system: tonsils (in our throats), thymus (in our chests), lymph nodes (in our armpits, necks and groins), and spleen (in our guts). Immune cells move around the lymphatic system via lymphatic vessels, always on the lookout for infection. There are two main parts of the system: the innate immune system and the acquired immune system. 11

The innate immune system is designed to fight off anything that isn’t supposed to be in our bodies - it isn’t picky about what it targets. When a pathogen enters our body, a type of white blood cell called a neutrophil will notice the invader right away and gobble it up, a process called “phagocytosis.”

Monocytes and eosinophils are other immune cell types which also eat up germs that find their way inside our bodies. While monocytes target anything, eosinophils particularly like eating parasites like worms.

The neutrophils, monocytes and eosinophils are our first line of defence, but there are many other cells that also get involved in launching an immune response against a pathogen. 12

As soon as the neutrophils and monocytes start eating the invading germ, another type of white blood cell called a basophil will take notice and start sounding the alarm to other immune cells.

Now, more immune cells are becoming involved and chemicals called cytokines are being released by the cells. Cytokines are important because they will start a process called the “inflammatory response.” If you’ve ever gotten an infection, you will recognize the inflammatory response by its symptoms: fever, swelling, redness, heat, and pain. Even though it’s


uncomfortable, the inflammatory response is an important step for our bodies to contain the infection. At this point, after the inflammatory response to an invading pathogen has happened, the innate immune system will hand over the reins to the acquired immune system to continue fighting the invader. 13

The acquired immune system is a bit different instead of killing the pathogen right away, it will teach our bodies to remember the pathogen first, in case it ever enters our bodies again. We humans have actually learned to enhance our acquired immune systems with vaccines!

Vaccines are a way of teaching the immune system to fight off a specific germ without having to be infected with the real germ. Scientists have found ways to take small bits of a particular germ that won’t make us sick but will trick our immune systems into remembering the germ. This means we are protected, or “immune” to the germ we were vaccinated for. But how does this work? First, we have to learn a few things about the acquired immune system.

Once the front-line defence cells have digested the germ, they present pieces of the pathogen on their cell surface. These pieces are known as “antigens,” and are unique to the pathogen that’s been digested. Next, a group of cells called lymphocytes spring into action to learn the characteristics of the antigen and create a way of recognizing the antigen in the future. 14

First, T-helper cells recognize the antigen and help B-cells recognize it too. B-cells then produce a protein called an “antibody” which will attach itself to the antigen on the pathogen when the pathogen is in our bodies.

Antibodies are really important for the acquired immune system because they are the components that allow the system to learn how to fight recurring infections.

neutrophils and monocytes to the invader, they know not to trigger an inflammatory response which means we won’t feel sick!

Once a pathogen is identified and an antibody that can attach to the pathogen’s antigen is made, our bodies will never have to mount an inflammatory response against that pathogen, again! If the same pathogen ever re-enters our bodies, an antibody will recognize it and alert the neutrophils and monocytes to come and gobble it up. Since it was an antibody that alerted the

But usually, a pathogen manages to get into some of our own body cells before it can be digested by immune cells. Luckily when this infection happens, our body cells know what to do to signal for help. The infected cells present the pathogen’s antigen on their surface which attracts another lymphocyte called a T-cell. T-cells recognize the antigen and send chemicals and other killer T-cells to destroy the infected body cells. While this may sound like a bad thing, sometimes

we have to make small sacrifices to make sure the rest of our bodies stay healthy! Our immune systems work hard to keep us healthy, but sometimes they get confused and think that something harmless is an invading pathogen. For some people, something like a peanut or kiwi could trigger an inflammatory response even though peanuts and kiwis shouldn’t be dangerous! This is known as an allergic reaction - learn more on the next page! 15

Allergic Reactions Written by Melissa Illustrated by Eugenia


oes your school ask you to bring nut-free snacks and lunches? Most schools have a nut-free policy as many people have severe food allergies to nuts.

You might even know someone who is allergic to peanuts and that person probably carries an epi-pen wherever they go. Why do allergic reactions make us feel uncomfortable? And more specifically, how do these allergic reactions occur? To answer these questions, we’ll have to zoom in and take a closer look at our immune cells in action!


When we are first exposed to an allergen (things that trigger an allergic reaction) our body recognizes this as a foreign invader and begins producing antibodies. Antibodies recognize allergens and they bind to basophils so that they can help basophils recognize the allergen in the future.

This is equivalent to Mrs. Claus (B-cell) baking a batch of gingerbread cookies (antigens) so that the North Pole Elf (antibody) and Rudolph (basophil) can recognize and sniff for invading South Pole Elves (pathogens). We don’t actually get an allergic reaction the very first time we’re exposed to the allergen, we’re just preparing our body for future attacks!


The next time we encounter the allergen, our body’s basophils are on high alert and are ready for an attack. They also signal for other immune cells, such as eosinophils, to secrete chemicals to attack the allergen.


The release of these chemicals can cause inflammation, fever, swelling, and asthma, which is why allergic reactions are uncomfortable and possibly life-threatening.

Remember, allergens - which can be anything, such as a peanut, dust, or pollen - are non-threatening. Our immune system is just overreacting during an allergic reaction.


This is like Mrs. Claus overreacting over a potential attack by the South Pole Elves, and accidentally mixing up the gingerbread cookie recipe.

Instead of attacking South Pole Elves, Rudolph and Frosty (eosinophil) freeze the poor mail carrier delivering Santa’s letters.

Without the letters, Santa (monocyte) won’t know what presents the children on his Nice List want for Christmas and this causes a commotion at the North Pole.

How can the symptoms of allergic reactions be alleviated? People with mild allergies might be able to treat their symptoms with medication from the drug store, but individuals who suffer from life-threatening allergic reactions (anaphylaxis) will require an epi-pen injection and immediate medical care.

There is another situation in which the immune system behaves inappropriately, and this is seen in autoimmune diseases where the immune system attacks the body because it cannot distinguish between healthy body cells and foreign invaders.

Allergic reactions are the consequence of our immune system overreacting over things that are normally harmless.

Read the next article to learn about celiac disease (an autoimmune disease that affects the small intestine). 19

Autoimmune Diseases:

Celiac Disease Written by Melissa Illustrated by Eugenia


ou’ve probably seen those nut-free labels on food packages at the grocery store, but have you noticed the glutenfree labels? There is a genetic autoimmune disease called celiac disease that is triggered by gluten in the small intestine. The term “genetic� simply means that the disease often runs in the family and an autoimmune disease is when the immune system attacks the body.


Gluten is a protein found in grains, and many foods such as pizza and pasta contain gluten. People with Celiac disease are put on a glutenfree diet.

Food spends a long time in the small intestine as it is a very long tube (about four times your height!) The small intestine also plays a key role in nutrient absorption.

The small intestine lining is made of a lot of cells called enterocytes. Each enterocyte has a lot of finger-like projections called villi that are important for absorbing nutrients.

If we zoom in on the enterocytes, gluten will first trigger an immune response. The immune response will damage the enterocytes, and this will cause enterocytes to release an enzyme called tissue

transglutaminase (tTG) that will change the gluten molecule. Changing gluten will confuse the immune cells to attack the enterocytes. 21

People with celiac disease have their enterocytes damaged by their immune system. Consequently, people with celiac disease may have nutrient deficiencies and delayed growth and common symptoms include diarrhea and weight loss. Without the proper absorption of vitamins and nutrients, these individuals are also more prone to other autoimmune diseases and other diseases, such as osteoporosis


(learn more about osteoporosis from the Musculoskeletal System Booklet if you haven’t read it yet!) There are some instances when the immune system behaves inappropriately and overreacts, as seen in allergic reactions and autoimmune diseases, but for the most part, the immune system does a good job at protecting us from infection. The immune system is definitely complicated!

Activity Booklet

What’s Inside?

Crossword Puzzle Word Search 23

Crossword Puzzle

Immune System Edition

Use the immune system to complete the crossword!



1. A preventative method to build immunity prior to being infected with a pathogen 4. These cells are the first to respond to an infection 8. The type of immune system that we are naturally born with 11. These cells produce antibodies


2. A type of pathogen that can cause shortness of breath and a dry cough

3. A type of disease where the immune system attacks itself 5. Antibodies recognize ___ on the surface of cells 6. These cells release chemicals and toxins during an allergic reaction 7. The location where all immune cells and blood cells are produced 9. These cells are always hungry and search out pathogens to engulf 10. These cells activate the acquired immune system 25

The Immune System Word Search

Can you find and circle these words? Antigens Basophils Coronavirus Inflammation Monocytes T cells 26

Allergies Autoimmune B cells Eosinophils Neutrophils Vaccine

Antibodies Bacteria Bone marrow Immune system Lymphocytes Pathogen

Answers Crossword

Copyright Š 2020 by The Science Communication Club All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law. Published on December 25, 2020 The Science Communication Club



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