The lymphatic system transports lymph fluid and filters pathogens. It includes lymph vessels, lymph nodes, the spleen, thymus, tonsils, and bone marrow. Lymph fluid contains lymphocytes and drains excess tissue fluid, absorbed fats, and cell debris from tissues. It transports these materials through lymph vessels and lymph nodes which filter the lymph. The spleen, thymus and tonsils are lymphatic organs that help produce and store lymphocytes to fight infection. The document describes the structures and functions of the lymphatic system components in detail.

1. LYMPHATIC SYSTEM
BY
SONI KUMARI SHAH

2. Lymphatic System
The lymphatic system is the system of vessels, cells, and organs
that carries excess fluids to the bloodstream and filters pathogens
from the blood.
The swelling of lymph nodes during an infection and the transport
of lymphocytes via the lymphatic vessels are but two examples of
the many connections between these critical organ systems.

3. Organs Of Lymphatic System
Lymph
Lymph vessels
Lymph nodes
Lymph organs, eg. Spleen and thymus
Diffuse lymphoid tissue, eg. Tonsils
Bone marrow.

4. Functions Of Lymphatic System
Tissue drainage: it helps the venous system to drain the colloid components and
particular matters of the tissue fluid.
Immunity: production and maturation of lymphocytes, lymphocytes is responsible
for immunity.
It helps in absorption of digested fat and fat soluble substances.
The lymphatic drain the excessive tissue fluid from the tissues back to the
circulation.
Lymph nodes protect the blood against infection by filtering and destroying
bacteria.

5. Lymph
Lymph is a clear watery fluid, similar in composition to plasma, with the
important exception of plasma proteins, and identical in composition to
interstitial fluid.
Lymph transports the plasma proteins that seep out of the capillary
beds back to the bloodstream.
It also carries away larger particles, e.g. bacteria and cell debris from
damaged tissues, which can then be filtered out and destroyed by the
lymph nodes.
Lymph contains lymphocytes (defense cells), which circulate in the

6. Composition Of Lymph
Water 96%
Solids 4%
Solid substances includes proteins, lipids, carbohydrate, amino acids,
electrolytes, etc.

7. Characteristics Of Lymph
It differs from blood as lymph has no RBCs.
It resembles plasma in composition but contains less protein.
It is nearly identical to the interstitial fluid of the region of the body in
which lymph occurs.
It does not pump to force movement- movement of lymph caused by
breathing and by contraction of skeletal system.
It moves slowly and in one direction due to one way valves to prevent
backflow.

8. Functions Of Lymph
Lymph is to return the protein from tissue space into blood.
Lymph flow plays an important role in redistribution of fluid in the
body.
Through the lymph, bacteria, toxin and other foreign bodies are
removed from the tissue. It also plays an important role in immunity by
transporting lymphocytes.

9. Lymphatic Vessels
Lymph vessels are often found running alongside the arteries and veins
serving the area.
Their walls are about the same thickness as those of small veins and have
the same layers of tissue, i.e. a fibrous covering, a middle layer of smooth
muscle and elastic tissue and an inner lining of endothelium.
Like veins, lymph vessels have numerous cup-shaped valves to ensure that
lymph flows in a one-way system towards the thorax.
Lymph vessels become larger as they join together, eventually forming two
large ducts, the thoracic duct and right lymphatic duct, which empty lymph
into the subclavian veins.

10. Lymph Capillaries
These originate as blind-end tubes in the interstitial spaces.
They have the same structure as blood capillaries, i.e. a single
layer of endothelial cells, but their walls are more permeable to all
interstitial fluid constituents, including proteins and cell debris.
The tiny capillaries join up to form larger lymph vessels.

11. Larger Lymphatic Vessels, Trunks
and Ducts
The lymphatic capillaries empty into
larger lymphatic vessels.
The one-way valves are located fairly
close to one another, and each one
causes a bulge in the lymphatic vessel,
giving the vessels a beaded
appearance.
The superficial and deep lymphatics
eventually merge to form larger
lymphatic vessels known as lymphatic

12. Larger Lymphatic Vessels, Trunks, and
Ducts
On the right side of the body, the right sides of
the head, thorax, and right upper limb drain
lymph fluid into the right subclavian vein via the
right lymphatic duct.
On the left side of the body, the remaining
portions of the body drain into the larger
thoracic duct, which drains into the left
subclavian vein.
The thoracic duct itself begins just beneath the
diaphragm in the cisterna chyli, a sac-like
chamber that receives lymph from the lower

13. Thoracic Duct
This duct begins at the cisterna chyli,
which is a dilated lymph channel situated
in front of the bodies of the first two lumbar
vertebrae.
The duct is about 45 cm long and opens
into the left subclavian vein in the root of
the neck.
It drains lymph from both legs, the pelvic
and abdominal cavities, the left half of the
thorax, head and neck and the left arm.

14. Right Lymphatic Duct
This is a dilated lymph vessel about
1 cm long.
It lies in the root of the neck and
opens into the right subclavian vein.
It drains lymph from the right half of
the thorax, head and neck and the
right arm.

15. Lymph Nodes
Lymph nodes are oval or bean-shaped organs that lie, often in
groups, along the length of lymph vessels.
The lymph drains through a number of nodes, usually 8–10, before
returning to the venous circulation.
These nodes vary considerably in size: some are as small as a pin
head and the largest are about the size of an almond.

16. Structure Of Lymph Node
Lymph nodes have an outer capsule of fibrous
tissue that dips down into the node substance
forming partitions, or trabeculae.
The main substance of the node consists of
reticular and lymphatic tissue containing many
lymphocytes and macrophages.
As many as four or five afferent lymph vessels
may enter a lymph node while only one efferent
vessel carries lymph away from the node.
The large numbers of lymph nodes situated in
strategic positions throughout the body are
arranged in deep and superficial groups.

17. Functions Of Lymph Node
Lymph is filtered by the reticular and lymphatic tissue as it passes
through lymph nodes.
The macrophages of lymph nodes help in destroying the bacteria
and other toxic substance.
It helps in development of lymphocytes.

18. Classification Of Lymph Nodes
Anatomical Classification
Superficial Lymph Nodes
They are found along the lymphatic vessels in the superficial fascia. Eg.
Axillary nodes, submandibular lymph nodes etc.
Deep Lymph Nodes
They are found in deeper tissues. Eg. Aortic lymph nodes.

19. Regional Classification
Cervical Lymph Nodes
It lies behind and below the ear, along the inferior margin of mandible and down the side of neck.
Axillary Lymph Nodes
It lies from the arm, through the armpit, to the thoracic wall, breast and superior abdominal wall.
Thoracic Lymph Nodes
It lies along the abdominal aorta and mesenteric arteries.
Pelvic Lymph Nodes
It lies along the iliac arteries and veins
Inguinal Nodes
It lies in the groin.

20. Spleen
The spleen contains reticular and
lymphatic tissue and is the largest lymph
organ.
The spleen lies in the left hypochondriac
region of the abdominal cavity between
the fundus of the stomach and the
diaphragm.
It is purplish in colour and varies in size
in different individuals, but is usually
about 12 cm long, 7 cm wide and 2.5 cm

21. Organs Associated With The Spleen
Superiorly and posteriorly – diaphragm
Inferiorly – left colic flexure of the large intestine
Anteriorly – fundus of the stomach
Medially – pancreas and the left kidney
Laterally – separated from the 9th, 10th and 11th ribs and the
intercostal muscles by the diaphragm

22. Structure Of Spleen
The spleen is slightly oval in shape with the hilum on
the lower medial border.
The anterior surface is covered with peritoneum. It is
enclosed in a fibroelastic capsule that dips into the
organ, forming trabeculae.
The cellular material, consisting of lymphocytes and
macrophages, is called splenic pulp, and lies between
the trabeculae.
Red pulp is the part suffused with blood and white
pulp consists of areas of lymphatic tissue where there
are sleeves of lymphocytes and macrophages around
blood vessels.

23. Structure Of Spleen
The structures entering and leaving the spleen at the hilum are:
• splenic artery, a branch of the coeliac artery
• splenic vein, a branch of the portal vein
• lymph vessels (efferent only)
• nerves.

24. Functions Of Spleen
Hemopoiesis: The spleen and liver are important sites of fetal blood
cell Production
Storage of blood: The spleen contains up to 350 mL of blood, and
in response to sympathetic stimulation can rapidly return most of
this volume to the circulation, e.g. in hemorrhage.
Filtration: it acts as a sophisticated filter of the body. It filter out and
destroys RBC, bacteria, cancer cells, and other particulate matters.
Destruction of worn out RBCs. Hence, it is called grave yard of RBC.

25. Clinical Anatomy Of Spleen
Splenomegaly is enlargement of spleen.
Splenic infraction
Splenectomy is surgical removal of spleen in certain diseases. It can be
removed because liver and bone marrow can perform splenic function.

26. Tonsil
Tonsils are lymphoid nodules located along the inner surface of the
pharynx and are important in developing immunity to oral
pathogens .
The tonsil located at the back of the throat, the pharyngeal tonsil, is
sometimes referred to as the adenoid when swollen. Such swelling
is an indication of an active immune response to infection.
Tonsils are often removed in those children who have recurring
throat infections, especially those involving the palatine tonsils on
either side of the throat, whose swelling may interfere with their
breathing and/or swallowing.

27. Structure Of Tonsil
Histologically, tonsils do not contain a complete capsule, and the
epithelial layer invaginates deeply into the interior of the tonsil to
form tonsillar crypts.
These structures, which accumulate all sorts of materials taken into
the body through eating and breathing, actually “encourage”
pathogens to penetrate deep into the tonsillar tissues where they
are acted upon by numerous lymphoid follicles and eliminated.
This seems to be the major function of tonsils—to help children’s
bodies recognize, destroy, and develop immunity to common
environmental pathogens so that they will be protected in their later
lives.

28. Types Of Tonsil
Nasopharyngeal Tonsil
It is near the opening of nasal cavity into pharynx.
Palatine Tonsil
It is located near the opening of oral cavity in the pharynx.
Lingual Tonsil
It is located on the posterior surface of tongue.
Tubal Tonsil
It is located near the pharyngeal tonsil.

29. Thymus Gland
The thymus gland lies in the upper part
of the mediastinum behind the sternum
and extends upwards into the root of the
neck.
It weighs about 10 to 15 g at birth and
grows until puberty, when it begins to
atrophy.
Its maximum weight, at puberty, is
between 30 and 40 g and by middle age
it has returned to approximately its
weight at birth.

30. Organs Associated With The Thymus
Anteriorly – sternum and upper four costal cartilages
Posteriorly – aortic arch and its branches, brachiocephalic veins,
trachea
Laterally – lungs
Superiorly – structures in the root of
the neck
Inferiorly – heart

31. Structure of Thymus
The thymus consists of two lobes
joined by areolar tissue.
The lobes are enclosed by a
fibrous capsule which dips into
their substance, dividing them into
lobules that consist of an irregular
branching framework of epithelial
cells and lymphocytes.

32. Functions Of Thymus
Thymus is involved in cellular immunity which protects our body against
foreign substances and microorganisms.
It produces lymphocytes (T cells)
It secretes thymosin which is necessary for the maturation of T-
lymphocytes.
It helps in proper growth and development of other lymphoid tissue.

33. Lymphatic Circulation
First of all blood plasma reaches the interstitial space after filtering via blood
capillaries wall.
Plasma passes into interstitial space between tissues and becomes interstitial fluid.
Interstitial fluid passes from interstitial space into lymph capillaries and it becomes
lymph fluid containing water with plasma solutes of ions, gases, nutrients, proteins
and substances from tissue cells such as hormones, enzymes and waste products.
Lymph drained by lymphatic capillaries passed to lymphatic vessels.
Lymph passes toward lymph node via afferent lymphatic vessels.
Lymph passes through lymph nodes.

34. Lymphatic Circulation
Lymph nodes identifies substances after activating immune response.
Lymphocytes produces and are released into lymph by germinal center of lymph node.
Lymph head towards major lymphatic duct(Right lymphatic duct and thoracic duct)
via efferent lymphatic vessels.
The thoracic duct empties all of its lymph into the left subclavian vein and the right
lymphatic duct empties all of its lymph into the right subclavian vein.
Lymphocytes reach blood and produce antibodies against microorganisms.
Macrophages removes dead microorganisms and foreign substances by phagocytosis.

35. Lymphatic Circulation

36. Immune System
The immune system defends the body against invasion by harmful organisms
and chemical toxins.
Immunity
Immunity is defined as the state of resistance exhibited by the host towards
injury, toxic molecules caused by microorganisms, foreign cells and their
products.
Immunity refers to the body’s capacity to resist invading organisms and toxins,
thereby preventing tissue and organ damage.

37. Antigen
Antigen are the substances which induce specific immune reaction in
the body. The antigen stimulates lymphocytes to produce antibodies or
to attack the antigen directly(antibody immunity)
Antibody
A protein substance present in the blood serum, produced in response
to a reaction with a specific antigen is known as antibody.

38. Types Of Immunity

40. Immunity
The immune system is designed to recognize, respond to, and eliminate
antigens, including bacteria, fungi, viruses, and parasites. It also
preserves the body’s internal environment by scavenging dead or
damaged cells and patrolling for antigens.
To perform these functions efficiently, the immune system uses three
basic strategies:
• protective surface phenomena
• general host defenses
• specific immune responses.

41. Protective Surface Phenomena
Strategically placed physical, chemical, and mechanical barriers work to
prevent the entry of potentially harmful organisms.
Skin And Mucous Membranes
Intact and healing skin and mucous membranes provide the first line of
defense against microbial invasion, preventing attachment of
microorganisms. Skin desquamation (normal cell turnover) and low pH
further impede bacterial colonization. Seromucous surfaces are
protected by antibacterial substances—for instance, the enzyme
lysozyme, which is found in tears, saliva, and nasal secretions.

42. Respiratory System
In the respiratory system (the easiest part of the body for
microorganisms to enter), nasal hairs and turbulent airflow through the
nostrils filter out foreign materials.
Nasal secretions contain an immunoglobulin that discourages microbe
adherence.
Also, a mucous layer, which is continuously sloughed off and replaced,
lines the respiratory tract and provides additional protection.

43. GI Tract
In the GI tract, bacteria are mechanically removed by saliva, swallowing,
peristalsis, and defecation.
In addition, the low pH of gastric secretions is bactericidal (bacteria-
killing), rendering the stomach virtually free from live bacteria.
The remainder of the GI system is protected through colonization
resistance, in which resident bacteria prevent other microorganisms
from permanently making a home.

44. Urinary System
The urinary system is sterile except for the distal end of the urethra and
the urinary meatus.
Urine flow, low urine pH, immunoglobulin and, in men, the bactericidal
effects of prostatic fluid work together to impede bacterial colonization.
A series of sphincters also inhibits bacterial migration.

45. General Host Defenses
When an antigen penetrates the skin or mucous membrane, the immune
system launches nonspecific cellular responses in an effort to identify and
remove the invader.
The first of the nonspecific responses against an antigen, the
inflammatory response, involves vascular and cellular changes, including
the production and release of such chemical substances as heparin,
histamine, and kinin. These changes eliminate dead tissue,
microorganisms, toxins, and inert foreign matter.

46. Inflammatory Response
The inflammatory response helps the body return to homeostasis after a wound
occurs.
Its primary function is to bring phagocytic cells (neutrophils and monocytes) to the
inflamed area to destroy bacteria and rid the tissue spaces of dead and dying cells so
that tissue repair can begin.
Inflammation produces four cardinal signs: redness, swelling, heat, and pain.
The first three signs result from local vasodilation, fluid leakage into the extravascular
space, and blockage of lymphatic drainage.
The fourth results from tissue space distention caused by swelling and pressure and
from chemical irritation of nociceptors (pain receptors).

47. Inflammatory Response
Polymorphonuclear leukocytes play a big role in the inflammatory
response:
Neutrophils, which are produced in the bone marrow, are the most
numerous polymorphonuclear leukocytes. They increase dramatically in
number in response to infection and inflammation. They’re the main
constituent of pus and are highly mobile. Neutrophils are attracted to
areas of inflammation. They engulf, digest, and dispose of invading
organisms through a process called phagocytosis.

48. Inflammatory Response
Eosinophils, found in large numbers in the respiratory system and GI tract,
multiply in allergic and parasitic disorders. Although their phagocytic
function isn’t clearly understood, evidence suggests that they participate in
host defense against parasites.
Basophils and mast cells also function in immune disorders. Basophils
circulate in peripheral blood, whereas mast cells accumulate in connective
tissue, particularly in the lungs, intestines, and skin. (Mast cells are not
blood cells.) Both cells have surface receptors for immunoglobulin (Ig) E.
When their receptors are cross-linked by an IgE antigen complex, they
release mediators characteristic of the allergic response.

49. Specific Immune Responses
All foreign substances elicit the same general host defenses. In addition,
particular microorganisms or molecules activate specific immune
responses and can involve specialized sets of immune cells.
Specific responses, classified as either humoral immunity or cell-
mediated immunity, are produced by lymphocytes (B cells and T cells).

50. Humoral Immunity
In this response, an invading antigen causes B cells to divide and
differentiate into plasma cells. Each plasma cell, in turn, produces and
secretes large amounts of antigen-specific immunoglobulins into the
bloodstream.
Cell-mediated Immunity
Cell-mediated immunity protects the body against bacterial, viral, and
fungal infections by inactivating the antigen and provides resistance
against transplanted cells and tumor cells.

51. Specific And Non Specific Immunity
Non specific (Innate) immunity
Specific(Acquired/Adaptive)
immunity
First Line Of Defense Second Line Of Defense Third Line Of Defense
 Intact skin
 Mucous membranes
and their secretions
 Normal microbiota
 Natural killer cells and
phagocytic white blood
cells
 Inflammation
 Fever
 Antimicrobial
substances
 Specialized lymphocyte: T
cells and B cells
 Antibodies

52. Differences Between Specific And Non Specific Immunity
SN Non-specific immunity specific immunity
1 Response is antigen-independent Response is antigen-dependent
2 There is immediate maximal
response
There is lag time between
exposure and maximal response
3 Not antigen-specific Antigen-specific
4 Exposure results in no
immunological memory
Exposure results in immunological
memory

53. Differences Between Active Immunity And Passive Immunity
SN Active immunity Passive immunity
1 Produced actively by host’s immune
system
Received passively to host’s immune
system
2 Induced by infection No active host participation
3 Durable and provide effective protection Short lived and provide immediate
immunity
4 Not applicable in immunodeficient
conditions
Applicable in immunodeficient conditions
5 Used for prophylaxis to increase body
resistance like BCG vaccine
Useful for treatment in case of severe
immunodeficient conditions
6 Immunological memory present No memory

54. Differences Between Primary And Secondary Immune Response
SN Primary Immune Response Secondary Immune Response
1 Small number of pathogen specific cells
respond at the start
Large number of pathogen specific cells
respond immediately
2 Delay before pathogen specific antibodies
are produced
Pathogen specific antibodies already present
3 Non-isotype switched antibody having a
mixture of affinities for the pathogen is
produced at the start
Antibodies is isotype switched and have high
affinity for the pathogen
4 High threshold of activation Lower threshold of activation
5 Delay before effector T cells are generated
and are able to enter infected tissue
Effector T cells are present and can enter
infected tissue immediately
6 Innate immunity works alone until an
adaptive response is generated
Close cooperation between innate and
adaptive immunity from the start

55. Immune System Malfunction
Because of their complexity, the processes involved in host defense and
immune response may malfunction.
When the body’s defenses are exaggerated, misdirected, or either absent
or depressed, the result may be a hypersensitivity disorder, autoimmunity,
or immunodeficiency, respectively.
Such disorders are classified as type I through type IV, depending on which
immune system activity causes tissue damage.

56. Hypersensitivity
Type I disorders are anaphylactic (immediate, atopic, IgE mediated
reaginic) reactions.
Examples of type I disorders include systemic anaphylaxis, hay fever
(seasonal allergic rhinitis), reactions to insect stings, some food and
drug reactions, some cases of urticaria, and infantile eczema.

57. Hypersensitivity
Type II disorders are cytotoxic (cytolytic, complement dependent
cytotoxicity) reactions.
Examples of type II disorders include Goodpasture’s syndrome,
autoimmune hemolytic anemia, transfusion reactions, hemolytic
disease of the neonate, myasthenia gravis, and some drug reactions

58. Hypersensitivity
Type III disorders are immune complex disease reactions.
Examples of type III disorders are reactions associated with such infections
as hepatitis B and bacterial endocarditis; cancers, in which a serum
sickness-like syndrome may occur; and autoimmune disorders such as
systemic lupus erythematosus.
This hypersensitivity reaction may also follow drug or serum therapy.

59. Hypersensitivity
Type IV disorders are delayed (cell-mediated) hypersensitivity reactions.
Type IV disorders include tuberculin reactions, contact hypersensitivity
(latex allergy), and sarcoidosis.

60. Autoimmunity
Autoimmunity leads to a sequence of tissue reactions and damage that
may produce diffuse systemic signs and symptoms.
Autoimmune disorders are marked by an abnormal response to one’s
own tissue.
Among the autoimmune disorders are type 1 diabetes mellitus,
rheumatoid arthritis, juvenile rheumatoid arthritis, psoriatic arthritis,
ankylosing spondylitis, Sjogren’s syndrome, multiple sclerosis,
autoimmune pancreatitis, and lupus erythematosus.

61. Immunodeficiency
Immunodeficiency disorders are caused by an absent or a depressed
immune response in various forms.
When the immune system is compromised, there is a tendency to
recurrent infections, often by microbes not normally pathogenic in
humans (opportunistic infections).
Immunodeficiency is classified as primary (usually occurring in
infancy and genetically mediated) or secondary, that is, acquired in
later life as the result of another disease, e.g. protein deficiency,
acute infection, chronic renal failure, bone marrow diseases,
following splenectomy or acquired immune deficiency syndrome
(AIDS).

62. Tissue Rejection Reaction
Tissue transplantation is more complicated than blood transfusions because of two
characteristics of MHC (Major histocompatibility complex) molecules. These
molecules are the major cause of transplant rejection.
When a donor organ expresses MHC molecules that are different from the
recipient, the latter will often mount a cytotoxic T cell response to the organ and
reject it.
Histologically, if a biopsy of a transplanted organ exhibits massive infiltration of T
lymphocytes within the first weeks after transplant, it is a sign that the transplant is
likely to fail. The response is a classical, and very specific, primary T cell immune
response.
As far as medicine is concerned, the immune response in this scenario does the

63. Stem cells are multipotential and develop into other types of cells through the process of:
A. chemotaxis.
B. phagocytosis.
C. hematopoiesis.
D. opsonization..
Cleansed lymph leaves the lymph nodes through:
A. afferent lymphatic vessels.
B. efferent lymphatic vessels.
C. lymphatic capillaries.
D. blood capillaries.
During which phase of phagocytosis does a macrophage engulf an opsonized microorganism within a vacuole?
A. Chemotaxis
B. Opsonization
C. Ingestion
D. Digestion

64. Which of the following cells is phagocytic?
a. plasma cell
b. macrophage
c. B cell
d. NK cell
Which structure allows lymph from the lower right limb to enter the bloodstream?
a. thoracic duct
b. right lymphatic duct
c. right lymphatic trunk
d. left lymphatic trunk
Which of the following cells is important in the innate immune response?
a. B cells
b. T cells
c. macrophages
d. plasma cells

65. Which of the following cells would be most active in early, antiviral immune responses the first time
one is
exposed to pathogen?
a. macrophage
b. T cell
c. neutrophil
d. natural killer cell
Which of the lymphoid nodules is most likely to see food antigens first?
a. tonsils
b. Peyer’s patches
c. bronchus-associated lymphoid tissue
d. mucosa-associated lymphoid tissue
Which of the following signs is not characteristic of inflammation?
a. redness
b. pain
c. cold
d. swelling

66. Which of the following is not important in the antiviral innate immune response?
a. interferons
b. natural killer cells
c. complement
d. microphages
Which of the following leads to the redness of inflammation?
a. increased vascular permeability
b. anaphylactic shock
c. increased blood flow
d. complement activation
Which class of antibody crosses the placenta in pregnant women?
a. IgM
b. IgA
c. IgE
d. IgG

67. What type of chronic lung disease is caused by a Mycobacterium?
a. asthma
b. emphysema
c. tuberculosis
d. leprosy
Which type of immune response is most directly effective against bacteria?
a. natural killer cells
b. complement
c. cytotoxic T cells
d. helper T cells
What is the reason that you have to be immunized with a new influenza vaccine each year?
a. the vaccine is only protective for a year
b. mutation
c. macrophage oxidative metabolism
d. memory response

68. Which type of hypersensitivity involves soluble antigen-antibody complexes?
a. type I
b. type II
c. type III
d. type IV
Which of the following is a critical feature of immediate hypersensitivity?
a. inflammation
b. cytotoxic T cells
c. recruitment of immune cells
d. histamine release

69. Which of the following is an autoimmune disease of the heart?
a. rheumatoid arthritis
b. lupus
c. rheumatic fever
d. Hashimoto’s thyroiditis
Why do we have natural antibodies?
a. We don’t know why.
b. immunity to environmental bacteria
c. immunity to transplants
d. from clonal selection
Which type of cancer is associated with HIV disease?
a. Kaposi’s sarcoma
b. melanoma
c. lymphoma
d. renal cell carcinoma