CYTOKINES AND IMMUNE RESPONSES

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CYTOKINES AND IMMUNE RESPONSES
Beverly E. Barton, Ph.D. Assistant
Professor Department of Surgery/Division of
Urology UMDNJ-NJMS MSB F672 185 S. Orange
Avenue Newark, New Jersey 07103 Telephone
973-972-0662 E-mail
bartonbe_at_umdnj.edu Telefacsimile 973-972-3892
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CYTOKINES Cytokines are a
group of low molecular weight regulatory proteins
secreted by leukocytes as well as a variety of
other cells in the body in response to stimuli.
Membrane-bound forms of some of the secreted
cytokines are known as well. Cytokines regulate
the intensity and duration of the immune response
by stimulating or inhibiting the activation,
proliferation, and/or differentiation of various
cells, and by regulating the secretion of
antibodies or other cytokines or
mediators. Almost ALL cells secrete at least a
few cytokines.
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3 MAJOR ROUTES OF CYTOKINE TRAVEL
STIMULUS
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A (VERY) SHORT HISTORY
OF CYTOKINES 1957-- Isaacs Lindemann described
IF-? in virally-infected chick
chorioallantoic membranes 1965 -- Wheelock
described IF-? in PHA-treated leukocytes 1966 --
MIF described by David Bloom in sups of
Ag-stimulated lymphocytes
Photomicrograph from original paper depicting
Ag-specific MIF production by guinea pig
peritoneal cells.
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Cytokines differ from growth factors in the
structure of the receptor.
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MOST CYTOKINE RECEPTORS ARE IN 2 CLASSES
CLASS I CYTOKINE RECEPTORS
Most of the cytokine-binding receptors that
function in the immune and hematopoietic systems
belong to this receptor family. There are
conserved amino acid sequence motifs in the
extracellular domain - 4 positionally conserved
Cys residues (CCCC) and a conserved sequence of
Trp-Ser-X-Trp-Ser (WSXWS) where X is a
nonconserved amino acid.  The receptors consist
of 2 polypeptide chains a cytokine-specific
subunit and a signal-transducing subunit, which
is usually not specific for the cytokine.  In a
few cases these receptors are trimers.  The
signal transducing subunit is required for high
affinity binding of the cytokine.
CLASS II CYTOKINE RECEPTORS
These receptors possess the conserved cysteine
motifs, but lack the WSXWS motif present in class
I cytokine receptors. The IFs bind to Class II
receptors.
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CYTOKINES BY FUNCTION CYTOKINES THAT
MEDIATE AND REGULATE INNATE IMMUNITY Type I
interferons Dr. Pestkas lecture Tumor necrosis
factor-a Interleukins 1, 6, 10, 12, 15, 18, and
more Chemokinesa special subclass wont deal
with here CYTOKINES THAT MEDIATE AND REGULATE
SPECIFIC IMMUNITY Interleukins 2, 4, 5, 13, 16,
17, and more Interferon-g (Type II
interferon Dr. Pestkas lecture) Lymphotoxin-a
(Tumor necrosis factor-b) CYTOKINES THAT
STIMULATE HEMATOPOIESIS c-kit ligand Interleukins
3, 7, 9, 11, more Colony stimulating factors
M-CSF, G-CSF, GM-CSF, EPO, TPO Overlapping
functions are common.
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IL-1 FAMILY
Potent inflammatory effects, especially IL-1?
IL-1?. IL-18 induces IF-?, bridging Inflammatory
innate/adaptive immune responses. IL-1 induces
TNF, IL-6 as well as Inflammatory mediators from
various cells, notably cells at the interface of
the environment. IL-1 self-regulates through
induction of IL-1Ra IL-10. IL-1 is
an endogenous pyrogen (fever inducer). IL-33
induces TH2 cytokine synthesis, polarizing to TH2
(Ab) responses. IL-1 Family Receptors Two
receptors (RI and RII), both members of Ig gene
superfamily. IL-1RI found on T and B cells,
fibroblasts, keratinocytes, endothelial cells,
chondrocytes, hepatocytes, and synovial lining
cells has a MW of 80 kDa. IL-1RII found on B
cells, neutrophils, bone-marrow cells has a
MW of 60 kDa. Difference in MW arises from
IL-1RII having shorter cytosolic region. Some
evidence that 2 receptors mediate different
biological events even though they both bind IL-1
IL-18. A 3rd non-signaling receptor is found
as well, possibly with regulatory function.
IL-33 signals only through RII.
RI
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ENDOCRINE IL-1 PRODUCES FEVER
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IL-2-LIKE CYTOKINES
The common ? subunit associates with
each specific cytokine receptor to form the
high affinity cytokine receptor. The ? subunit
has a very short cytoplasmic tail it probably
does not signal.
IL-2 secreted primarily by T helper lymphocytes
activated by stimulation with T cell mitogens, or
by interaction of T cell receptor complex with
Ag/MHC complexes on surfaces of
antigen-presenting cells. The response of TH
cells to activation is induction of IL-2 and
high affinity receptors for IL-2 and,
subsequently, clonal expansion of
antigen-specific T cells. Here IL-2 is an
autocrine factor, driving the expansion of the
Ag-specific T cells. IL-2 also acts as a
paracrine factor, influencing the activity of
other cells, both within outside of the immune
system. B cells and natural killer (NK) cells
respond, when properly activated, to IL-2. The
so-called lymphokine activated killer,or LAK
cells, appear to be derived from NK cells under
the influence of IL-2.
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IL-4 Stimulates production of Ab-producing B
cells, leading to the production of Ig
class-switching to IgE. It also promotes CD8
cell growth and TH2 cell differentiation. On
macrophages, IL-4 induces MHC class II
expression, but inhibits production of pro-
inflammatory cytokines (IL-1, TNF?). Induction
of IL-4 secretion is Ag-specific and MHC
restricted. Antigenic stimulation also results
in increased responsiveness of TH cells to IL-4.
Ag-induced proliferation of TH cells is
inhibited by anti-IL-4. Thus, IL-4 mediates the
proliferation of TH cells by an Ag-induced
autocrine mechanism. During T cell--B cell
interactions involving soluble protein antigens,
IL-4 and not IL-2 is the critical cytokine for
activating resting B cells and inducing
proliferation of the TH cells.
IL-9 Up-regulates TH1 responses by inhibiting T
cell apoptosis. IL-9 is preferentially produced
by TH2 cells and is active on various cell types
such as T and B cells, mast cells and
hemopoietic progenitors. IL-13 Has structural
and functional similarities to IL-4 and promotes
B cell differentiation. Also promotes Ig class
switching to IgE. IL-15 Shares several
activities with IL-2 and is produced by
epithelial cells and monocytes. IL-15 induces T
cell proliferation, enhances NK cell cytotoxicity
and stimulates B cells to proliferate and
secrete Ig.
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IL-7 Is a T cell growth and activation factor,
and a macrophage activating factor. Interleukin-7
exerts pleiotropic effects on the immune system
it affects pre-B cells, thymocytes, mature T
cells, lymphokine activated killer cells (LAK),
monocytes, and macrophages.  IL-7 stimulates
the proliferation of pre-B cells harvested from
bone marrow.  IL-7 activates these cells in
vitro.  IL-7 restores V(D)J rearrangement to
developing T cells outside of the thymic
environment.  Normal maintenance and
proliferation of thymic progenitor cells requires
the presence of IL-7.  In combination with
phorbol 12-myristate 13-acetate, IL-7 drives the
activation of resting CD4 and CD8 T-cells
along a pathway that is independent of IL-2.
IL-7 maintains naïve CD4 T-cells in vitro for
up to 15 days, which suggests that it is a
survival factor for these cells. Peripheral
blood monocytes are activated by IL-7 lyse tumor
cells, secrete IL-6, IL-1?, IL-1?, and
TNF-?.  Cyclosporine A (CsA), an
immunosuppressive drug, inhibits the
transcription of many cytokines (for example, 
IL-2 and IL-4), but does not affect IL-7.
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IL-3, IL-5, GM-CSF
IL-3 Produced by activated T cells. Stimulates
the proliferation of all hematopoietic
precursors. Stimulates differentiation of
osteoclasts from bone marrow. IL-5 Is chiefly
a growth and activation factor for eosinophils
and B cells. Eosinophils in particular are noted
for their contribution to late phase
allergic-type disorders. Eosinophils make up
less than 10 of the circulating leukocyte
population, yet are extremely important in the
inflammatory response to allergic and parasitic
challenges. Eos are the cells of the
Ab-dependent cell-mediated cytotoxicity responses
(ADCC-- tumors, parasites). Cells known to
express IL-5 include eosinophils, NK cells, CD8
T cells, mast cells, CD4 T cells, ?? T cells,
and IL-1?-activated endothelial cells. IL-5 is
best known for its activity on B cells and
eosinophils. IL-5 appears to induce the
differentiation of activated conventional B-2
cells into Ig-secreting cells. In addition, it
induces the growth of B-1 progenitors as well as
IgM production by B-1 cells. In mice, IL-5
promotes production of IgA, IgE and
IgG1. GM-CSF Is chiefly a differentiation
factor for myeloid cells -- neutrophils,
macrophages. G granulocyte.
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IL-6-LIKE CYTOKINES
IL-6 IL-11 leptin
IL-6 Stimulates many types of cells. Endocrine
response by liver to it results in the acute
phase response. Required for Ig class switching
and for B cells to differentiate into plasma
cells. Endogenous pyrogen. While a number of
Interleukins such as IL-1 and IL-10 are seemingly
pleiotrophic in their effects, IL-6 may be
considered the prototypic pleiotrophic cytokine.
This is reflected in the variety of names
originally assigned to IL-6 based on function,
including Interferon ?2, IL-1-inducible 26 kD
Protein, Hepatocyte Stimulating Factor,
Cytotoxic T-cell Differentiation Factor, B cell
Differentiation Factor (BCDF) and/or B cell
Stimulatory Factor 2. Once all the activities
associated with the names for IL-6 became
connected with one common gene, the name IL-6
was proposed. A number of cytokines make up an
IL-6 cytokine family. Membership in this family
is based on a helical cytokine structure and
receptor subunit makeup. Just about every cell
type seems to express IL-6 expression of the
others more limited. IL-6 production is
correlated with 10 cell activation but others
with 20. IL-6 has been described as both a
pro-inflammatory and anti-inflammatory molecule,
a modulator of bone resorption, a promoter of
hematopoiesis, and an inducer of plasma cell
development. IL-6 also has been shown to
influence IL-4 production. It has been suggested
that antigen-driven, APC-derived IL-6 may
influence naive CD4 T cells to produce IL-4 and
express the IL-4 receptor. Thus, given the close
approximation of APC and T cell, transient
APC-derived IL-4 could initiate a T cell
autocrine loop whereby naive T cells direct
their own phenotype commitment.
CNTF CT-1 LIF NNT-1 OSM IL-31
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IL-6 PRODUCED BY MACROPHAGES, T CELLS, AND B
CELLS DURING RESPONSES TO Ag DRIVES B CELL
EXPANSION AND Ig CLASS SWITCHING
IL-6 IS REQUIRED FOR B CELL DIFFERENTIATION INTO
PLASMA CELLS.
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TNF FAMILY
The TNF family includes cell surface proteins,
such as CD40. TNF? is the principle cytokine
that mediates acute inflammation. In excessive
amounts it also is the principal cause of
systemic complications such as the shock
cascade. Major functions of TNF? acts on
endothelial cells to stimulate inflammation and
coagulation stimulates endothelial cells to
produce selectins and ligands for leukocyte
integrins during diapedesis stimulates
endothelial cells and macrophages to produce
chemokines stimulates macrophages to secrete
IL-1 activates neutrophils induces acute phase
response by liver cachectic factor (muscle
proteolysis and fat catabolism) cytotoxic for
some tumor cells interacts with hypothalamus to
induce fever and sleep stimulates the synthesis
of collagen in wound healing and tissue
repair activates macrophages and dendritic
cells is required by thymocytes for normal T cell
differentiation TNF? is produced by monocytes,
macrophages, dendritic cells, TH1 cells, and
others. TNF? is secreted and also active in
membrane-bound form.
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TNF Receptors 2 types of TNF receptors one has
a Death Domain is responsible for
cytotoxicity. They are type II membrane
proteins. The other signals through NF-?B is
responsible for the activation/differentiation
properties. Ligand/receptor complexes trimerize
to transduce either signal.
Lymphotoxin-? (LT?) TNF? LT? plays a role in
the recruitment and activation of neutrophils and
in lymphoid organogenesis. Produced by T cells,
including Tc plays a role in Tc function. Also
produced by NK cells and B cells. Lymphotoxin-?
(LT?) Is not secreted, although a specific
receptor exists. Active as membrane-bound cytokin
e. Aside from cytotoxic properties, it is
essential for the formation of germinal centers.
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IL-10 FAMILY
Recently a family of related cytokines has
emerged, comprising a series of herpesviral and
poxviral members and several cellular sequence
homologs, including IL-10, IL-19, IL-20, IL-22,
IL-24 and IL-26. Although the predicted
structure of these molecules is conserved,
certain receptor-binding residues are variable
and define the interaction with specific
heterodimers of different type-2 cytokine
receptors.
IL-10 was discovered initially as an inhibitory
factor for the production of TH1 cytokines.
Subsequently, pleiotropic inhibitory and
stimulatory effects on various types of blood
cells were described for IL-10, including its
role as a survival and differentiation factor for
B cells. IL-10, which is produced by activated
monocytes and T cells, as well as other cell
types, such as keratinocytes, appears to be a
crucial factor for at least some forms of
peripheral tolerance and a major suppressor of
the immune response and inflammation. The
inhibitory function of IL-10 is mediated by the
induction of regulatory T cells (CD4
CD25). IL-10 is also a survival and
differentiation factor for B cells.
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IL-22 mediates acute-phase response signals in
hepatocytes and IL-20 induces the
hyper- proliferation of keratinocytes proposed
as a pathogenic mechanism of psoriasis.
Many immunosuppressive and immunostimulatory
functions described for IL-10 biological
activities of the others are distinct from those
of IL-10, at least as far as is known for IL-20,
IL-22/IL-TIF and IL-24/MDA-7. Moreover, the site
of expression is distinct for each. IL-10 is
produced by TH2 cells, macrophages,
keratinocytes. The expression patterns are more
restricted for the others. IL-26/AK155 -
monocytes and various types of T
cells IL-22/IL-TIF - CD4 T cells IL-24 -
melanocytes, LPS-stimulated monos, TH2 cells
after stimulation with anti-CD3 IL-4 IL-19 -
LPS-treated monos, B cells. IL-20 - unclear--
low levels only in some tissue samples from skin
and trachea .
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IL-12 FAMILY
IL-12 Heterodimer p35 and p40
Receptor ?1 and ?2 subunits Acts in a
contrasting manner to IL-4 promotes TH1
differentiation induces IF-? production Primary
mediator of early innate immune responses to
intracellular microbes Inducer of cell-mediated
immunity Stimulates synthesis of IF-? by T cells
NK cells Increases the killing activity of
CTLs NK cells Stimulates differentiation of
naive CD4 T cells into IF-??producing TH1 cells.
Produced mainly by macrophages and dendritic
cells. IL-23 Heterodimer p19 and p40 (same
p40 as IL-12) Receptor ?1 and IL-23-specific
subunits Produced by activated DCs Induces
synthesis of pro-inflammatory cytokines (eg,
IL-17) by CD4 TH1 cells Does NOT induce IF-?
production Implicated in many autoimmune
disorders IL-23-specific subunit of receptor
homologous to IL-12 ?2 subunit May play a key
role in innate immunity to microbial pathogens
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Collison Vignali. IL-35 Odd one out or part of
the family? Immunol. Rev. 226(1) 248-262, 2009.
IL-27 is related to both IL-12 and IL-6 cytokine
families.
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IL-23 required for terminal differentiation of
TH17 cells Nature Immunology 10, 236 - 238
(2009) Don't leave home without it the IL-23
visa to TH17 cells Yeonseok Chung Chen
Dong Interleukin 23 is tightly associated with
TH17 cellmediated inflammation and
autoimmunity. A new study of mice deficient in
its receptor shows that interleukin 23 is
required for the terminal differentiation of TH17
cells in vivo. Nature Immunology 10, 314 - 324
(2009) The interleukin 23 receptor is essential
for the terminal differentiation of interleukin
17producing effector T helper cells in
vivo Mandy J McGeachy Whether interleukin 23
(IL-23) affects the differentiation of or simply
the maintenance of TH17 cells is unclear. The
data in this paper by McGeachy and colleagues
show that IL-23 is required for the full
differentiation and proliferation of effector
TH17 cells in vivo.
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IL-35 Heterodimer p35 and EBI3
Receptor UNKNOWN Inhibits T cell
differentiation expressed by Tregs Expands
Tregs inhibits TH17cells has therapeutic
effects in collagen arthritis model. Tregs from
IL-35 KO mice fail to ameliorate inflammatory
bowel disease in mouse model. EBI3
Epstein-Barr virus Induced gene 3
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IL-14 Induces B-cell proliferation, inhibits Ig
secretion, and selectively expands memory B
cells Produced by T cells Has homology with
complement factor Bb IL-16 Soluble ligand to
the CD4 molecule (its receptor) Chemotactic
properties for CD4 cells Growth factor for CD4
T cells, upregulating MHC class II and the IL-2
receptor CD25. Possible sources include CD8 T
cells, eosinophils, macrophages, mast cells
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IL-17 FAMILY
IL-17 (IL-17A) - secreted exclusively by a subset
of T cells -- TH17 cells Human IL-17A gene
product - 150 amino acids with a MW of 15 kDa,
secreted as disulfide- linked homodimer of 3035
kDa 5 related cytokines share 2050 homology
to IL-17 IL-17 - designated IL-17A to indicate
that it is the founding member of the IL-17
cytokine family IL-17F - produced primarily by
activated memory T cells IL-17B, IL-17C, IL-17D,
and IL-17E - secreted by a wider assortment of
cells IL-17R - transmembrane proteins of 130
kDa expressed on nearly all cells
(IL-17RA-D) IL-17A induced by IL-23 plays
proinflammatory role in joint destruction of
RA Signaling by IL-17 via IL17 receptor plays an
important role in host defense against
pathogens (J. Exp. Med. Published online Feb. 9,
2009 doi10.1084/jem.20081463)
IL-25 (aka IL-17E) Involved in development of
TH2 responses Involved in expulsion of helminthic
parasites Amplifies/exacerbates allergic
responses
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Taken from Gaffen. An Overview of IL-17 function
signaling. Cytokine. 43(3) 402-407, 2008.
IL-17 family ligands Produced by Binding
receptor(s) IL-17 (IL-17A, CTLA-8) T cells
(TH17) IL-17RA, IL-17RC
(IL-17RL) IL-17A/F heterodimer T cells IL-17RA,
IL-17RC IL-17B Numerous tissues IL-17RB? IL-17C
Prostate, fetal kidney IL-17D Numerous
tissues IL-17E/IL-25 Numerous tissues IL-17RB
(IL-25R) IL-17F T cells IL-17RA,
IL-17RC vIL-17 (ORF13) H. Saimiri IL-17RA,
IL-17RC? Unknown IL-17RD Unknown IL-17RE
It is currently believed that IL-17 regulates
innate immunity. Activates PMNs and expression
of anti-microbial genes.
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Gaffen. An Overview of IL-17 function
signaling. Cytokine. 43(3) 402-407, 2008.
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IL-27 IL-30
IL-27 - related to both IL-6 and IL-12 families
(which are related to each other by receptor
homology) IL-30 is p28 subunit of IL-27 IL-27
opposes actions of IL-23, thus has potent
anti-inflammatory activity Predict that IL-27
inhibits TH17 differentiation
maintenance. Receptor is believed to consist of
2 peptides, gp130 and WSX-1 (aka IL-27R) (For
this reason, one might include these 2 in the
IL-6 family)
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IL-28 IL-29
IL-28 and IL-29 are a recently discovered family
of novel class II cytokines distantly related to
IF-? and IL-10. IL-29 aka IF-?1 discovered by
UMDNJ faculty member Serge Kotenko IL-28 aka
IF-?3 Both have antiviral activity against
encephalomyocarditis and other viruses.
Receptor is composed of two chains, IL-28R and
IL-10R?
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IL-35 AND COUNTING
IL-32 is the name given to the NK4 transcript
first reported in IL-2 activated T lymphocytes
and natural killer cells 13 years ago without
known function. The novel cytokine has six
isoforms. Dinarello CA Kim SH. IL-32, a novel
cytokine with a possible role in disease. Ann
Rheum Dis. 2006. Nov65 Suppl 3iii61-iii64. no
homology with other cytokines induced by IL-2 and
IL-18 induces IF-?, IL-8, MIP-1? induces IL-1?
and IL-6 through a caspase-dependent
mechanism IL-33 see IL-1 IL-34 next
slide IL-35 see IL-12
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IL-34 IL-34 is known also as FPT025. The
protein does not show sequence homology with
known cytokines or growth factors. It is
expressed in spleen, skin, brain, and other
tissues. IL-34 human primary monocyte
proliferation and/or survival. Human IL-34
specifically binds to human primary monocytes and
activates ERK1/2 phosphorylation in a human
monocytic cell line, THP-1. IL-34 regulates
myeloid lineage differentiation, proliferation,
and survival promotes CFU-GM and CFU-M colony
formation from human bone marrow cells in a
colony formation assay stimulates expression of
myeloid cell surface markers. IL-34 appears to
act via the receptor for M-CSF. Lin H et al
Discovery of a cytokine and its receptor by
functional screening of the extracellular
proteome. Science 320(5877) 807-811 (2008).
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CYTOKINE CASCADE LINKS INFLAMMATORY AND IMMMUNE

RESPONSES
INFLAMMATORY
IMMUNE
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CYTOKINES DETERMINE NATURE OF ADAPTIVE IMMUNE
RESPONSE