Immune System Crossword Puzzle

Print a criss-cross vocabulary crossword on the immune system, from skin and mucus to antibodies, memory and vaccines.

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Immune System Crossword

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Answer key: Immune System Crossword

1VI2FE3VERAU4MUCUS5P6SC7AAK8IMMUNITYINTH9ANTIGENIOCBGI10LYMPHNODEDDN11MEMORY

Across 2 FEVER · 4 MUCUS · 8 IMMUNITY · 9 ANTIGEN · 10 LYMPHNODE · 11 MEMORY

Down 1 VIRUS · 3 VACCINE · 5 PATHOGEN · 6 SKIN · 7 ANTIBODY · 9 ACID

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Skin, Mucus and Other Barriers 23

  • Acid Stomach ___: juice that serves as a defense against swallowed germs
  • Barrier Anything that blocks the way in; several of them form the first line of defense
  • Cilia Tiny hairlike projections that sweep debris away from the lungs
  • Cough Noisy rush of air up from the lungs that drives out irritants
  • Cuticle Waxy coat of most leaves, a shield against infection
  • Defensin Germ-killing peptide that the body's outer covering and airways release
  • Earwax Waxy stuff in the ear canal that helps keep microbes and water out
  • Expel Force out, as a burst of air does to irritants in the airways
  • Flora Resident gut microbes that hold back harmful ones by competing for food and space
  • Lining Inner surface of the airways or the gut, coated with a protective gel
  • Lysozyme Antibacterial enzyme found in spit, eye fluid and breast milk
  • Mechanical Word for a defense that works by physical force, like a blast of air from the lungs
  • Membrane Mucous ___: surface layer that produces a slippery protective gel
  • Mucus Gel, made in the nose, throat and gut, that catches dust and germs
  • Oil Greasy coating of the body's surface; like eye fluid, it carries enzymes
  • Reflex Unplanned body response; a protective one clears irritants from the airways
  • Saliva Spit; it is around 99% water and carries agents against microbes
  • Shell Hard cover of an egg, one of nature's physical shields against infection
  • Skin Flexible body wrap that is part of the first line of defense
  • Sneeze Explosive rush of air set off by particles that irritate the nose
  • Tears Eye fluid that flushes germs away and carries enzymes against them
  • Trap Catch and hold, as the slippery gel of the airways does with inhaled particles
  • Urine Body fluid whose flushing action carries microbes out

Inflammation and Fast Responders 30

  • Basophil Rare white blood cell, about 0.5% to 1% of those in circulation, found in 1879
  • Cascade Run of steps, each setting off the next; a second name for one blood-protein defense
  • Chills Feeling of cold as the body's temperature set point rises
  • Complement ___ system: a set of small blood proteins that helps clear microbes and damaged cells
  • Cytokine Any of a broad family of small proteins that cells release to steer a response
  • Devour Eat greedily; the Greek word for it names the body's germ-swallowing cells
  • Dolor Latin for pain, one of the classic signs of an inflamed spot
  • Eosinophil White blood cell, less commonly called an acidophil, that takes on many-celled invaders
  • Fever Raised body temperature, a symptom of the fight against infection
  • Granule Tiny grain; some white blood cells are named for the ones in their cytoplasm
  • Heat Warmth at a sore spot; calor in Latin
  • Histamine Substance released by damaged cells that makes vessels leak; it is also behind itching
  • Hypothalamus Part of the brain where the set point for body temperature is kept
  • Inflammation Defense response of injured tissue, known by its classic signs of warmth and color
  • Injury Harm to tissue, from a blow, a burn or a germ, that sets off a defense response
  • Innate Word for the defenses you are born with
  • Interferon Signal protein from an infected cell that makes nearby cells raise their defenses
  • Macrophage Cell found in essentially all tissues that takes in and digests microbes and debris
  • Mast ___ cell: a cell of the tissues with many small storage grains of a leak-causing substance
  • Monocyte Largest defender cell in the bloodstream, amoeba-like in looks
  • Natural ___ killer cell: a fast responder to infected cells
  • Neutrophil Short-lived, highly mobile cell whose nucleus is divided into 2 to 5 lobes
  • Nonspecific Word for a defense that works against every marker alike
  • Phagocyte A liter of human blood holds about six billion of these germ-eating cells
  • Plants Living things in which the born-with defenses are the only ones
  • Pus Whitish-yellow collection of dead tissue, dead germs and defender cells
  • Pyrogen Name for anything that triggers a rise in the body's temperature set point
  • Redness Color change at a sore spot; rubor in Latin
  • Splinter Sliver of wood that the defenses treat as a foreign object
  • Swelling Puffing up of a sore spot as fluid leaks into the tissue

Antibodies, Lymphocytes and Memory 30

  • Acquired Word for protection that develops with exposure, not the kind you are born with
  • Adaptive Word for the half of the defenses that targets each invader specifically
  • Allergen Insect sting or certain food, to a person whose defenses overreact to it
  • Allergy Exaggerated response of the defenses to an ordinarily harmless substance
  • Antibody Ig for short: a large molecule the defenses use to identify an intruder
  • Antigen Marker, often a protein on a germ's surface, that the defenses recognize
  • Autoimmune Word for a response of the defenses against the body's own healthy cells
  • Bind Attach firmly, as a Y-shaped protein does to its one matching marker
  • Bone ___ marrow: tissue where all white blood cells are produced
  • Chain Heavy or light: each of the four strands of a Y-shaped defensive protein
  • Clone Identical copy; one selected B cell multiplies into many
  • Decades How long some quiet record-keeping B cells can circulate
  • Epitope The exact part of a marker molecule that the defenses recognize
  • Five Number of classes of Y-shaped defensive proteins in humans
  • Helper ___ T cell: one that aids other defender cells by releasing signal proteins
  • Humoral Word for defenses carried in the body's fluids, once called humors
  • Jawed ___ vertebrates: the animals in whose ancestor the tailor-made defenses evolved
  • Leukocyte Any of the body's defender cells, generally larger than red blood cells
  • Lymph node Kidney-shaped organ, one of many linked by vessels through the body
  • Lymphocyte B or T, for one: a defender cell of the tailor-made response
  • Memory Record of a past germ that makes the next response faster
  • Naive Word for a B cell that has not yet been activated by its marker
  • Neutralize Make harmless, as Y-shaped proteins do to the invaders they recognize
  • Paratope Tip of a Y-shaped defensive protein, the part that grips its target
  • Plasma ___ cell: a B cell turned factory that pours out defensive proteins
  • Pollen Grains shed by flowers, a common trigger of red eyes and a runny nose
  • Puberty Time of life until which the T-cell organ grows; afterward it gets smaller
  • Self The body's own tissues, which defender cells learn to leave alone
  • Spleen Organ found in almost all vertebrates that removes old red blood cells
  • Thymus Organ in front of the heart from which T cells take their name

Vaccines and Kinds of Immunity 22

  • Active Word for the kind of protection that a dose of weakened germs provides
  • Adjuvant Added ingredient that strengthens the body's response to a preparation
  • Antiserum Blood fluid with ready-made defensive proteins, given for immediate protection
  • Antitoxin Defensive protein able to make one specific poison harmless
  • Attenuated Word for a live germ altered so that it is harmless or less harmful
  • Booster Extra dose given later to bring protection back up
  • Colostrum First milk of a mammal mother, which carries protection for her newborn
  • Eradicated Wiped out worldwide, as one human disease was certified to be in 1980
  • Herd Word, borrowed from cattle, for the protection a whole community shares
  • Horse Large animal whose blood supplied ready-made defensive proteins for patients in 1890
  • Immunity State of being resistant to a disease
  • Immunize Make resistant to a disease, as a small dose of a marker does
  • Inactivated Word for a preparation whose germs have been killed so that they cannot multiply
  • Infant Baby; one is born with borrowed protection that disappears between 6 and 12 months
  • Injection The way most protective doses are given
  • Passive Word for protection borrowed from ready-made proteins produced in another body
  • Placenta Organ through which a mother's defensive proteins pass to her baby before birth
  • Protect Keep from harm; what the immune system does against disease
  • Shot Everyday word for a dose given through a needle
  • Smallpox The only human disease that has been wiped out worldwide
  • Toxoid Bacterial poison made harmless but still able to train the defenses
  • Vaccine Weakened or killed microbes, given so the defenses are ready later

Germs, Discoveries and Word Origins 28

  • Athens Greek city whose plague of 430 BC gave the earliest known mention of resisting a disease
  • Bacteria One-celled microbes, a few micrometers long, at home in soil and water
  • Behring German winner of the first Nobel Prize in Physiology or Medicine, in 1901, for serum therapy
  • Blossom Name of the animal from which Sarah Nelmes caught her mild disease
  • Burnet Australian doctor who introduced the clonal selection theory in 1957
  • Contagious Word for a disease easily passed on by contact with a sick person
  • Cowpox Disease once caught from cows; an English physician reasoned it would shield people from a deadlier one
  • Ehrlich German scientist who shared the 1908 prize with the discoverer of germ-eating cells
  • Exempt Free from a duty such as taxes; the sense of the Latin immunis
  • Fungus Yeast or mold, for one: an organism with chitin in its cell walls
  • Guinea pig Small animal, with goats, used in the poison experiments reported in 1890
  • Immunology Branch of biology that studies the defenses of all organisms
  • Inoculate Put material from a sick person into a healthy one on purpose, hoping for a mild case
  • Jenner English physician who tested the protective effect of a cattle disease on 14 May 1796
  • Metchnikoff Zoologist who discovered the body's germ-eating cells in 1882
  • Microscope Instrument that first showed living things too small for the eye, in the 1670s
  • Milkmaid Dairy worker; one named Sarah Nelmes supplied the material for the test of 1796
  • Montagu Lady Mary Wortley ___, who brought a protective practice from Turkey to Britain
  • Parasite Hookworm or mosquito, for one: a creature that lives at its host's expense
  • Pasteur Frenchman (1822 to 1895) whose first work on protective doses was with chicken cholera
  • Pathogen Word, in use since the 1880s, for anything that makes its host sick
  • Phipps Surname of the gardener's eight-year-old son in the test of 14 May 1796
  • Protozoan Single-celled organism; some kinds live off a host and cause disease
  • Rabies Disease of the dog that bit a 9-year-old boy who was treated on 6 July 1885
  • Starfish Sea animal whose larvae showed a zoologist cells gathering around an intruder in 1882
  • Thorn Citrus spike pushed into a larva in the experiment of 1882
  • Variolation Early method of giving a mild case of a deadly disease on purpose
  • Virus Most numerous biological entity on Earth; it multiplies only in cells

How this list was compiled: Clues written for this site for grades 6 to 12, in six sets. Facts were checked against the Immune response page of MedlinePlus (U.S. National Library of Medicine) and English Wikipedia (CC BY-SA 4.0) in October 2026. Clues say what a word names; nothing here is advice about illness, vaccines or treatment. Germ and immune are clue words and never answers. Licence: own work

How it works

This immune system crossword printable fits Letter or A4, answer key included. The first puzzle has 12 basic words, among them Antibody, Antigen, Vaccine, Pathogen, Immunity and Lymph node. White blood cell stays in the clues, never an answer.

Read the full guide

Five sets after the basics

Skin, Mucus and Other Barriers has Cilia, Lysozyme, Defensin and Flora. Inflammation and Fast Responders has Histamine, Phagocyte, Interferon and Complement. Antibodies, Lymphocytes and Memory has Epitope, Plasma, Helper and Thymus. Vaccines and Kinds of Immunity has Toxoid, Antiserum, Colostrum and Smallpox.

Names and dates a class can check

Germs, Discoveries and Word Origins runs from the plague of Athens in 430 BC to 1957: Jenner's test of 14 May 1796, Metchnikoff and the Starfish larvae of 1882, Behring's prize of 1901, and Exempt, the sense of the Latin immunis.

  • Print Skin, Mucus and Other Barriers with a lesson on the first line of defense, and the vaccines set once the class knows memory cells.

Questions and answers

What grade is the immune system crossword puzzle for?

Immune System Basics suits grades 6 to 8, with answers such as Fever, Skin, Mucus and Vaccine. The five themed sets use high school biology vocabulary, such as Phagocyte and Epitope. These bands are our judgment, not a published standard.

Does the immune system crossword puzzle have an answer key?

Yes. Every print ends with the key on its own sheet: the filled grid and the answers by clue number. It is free and needs no sign-up.

What is the difference between innate and adaptive immunity?

Innate immunity is the defense you are born with: barriers such as skin and mucus, and fast responses such as inflammation. Adaptive immunity develops with exposure: lymphocytes learn one antigen and keep a memory of it.

What is the difference between an antigen and an antibody?

An antigen is a substance, usually a protein on the surface of a cell, virus or bacterium, that the immune system recognizes. An antibody is a protein made by B cells that attaches to one specific antigen.

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