regarding a new way to studdy about antibody and antigen

1. IMMUNOLOGY

2. Infection
• Classification of infections
• Sources of infection
• Methods of transmission of infection
• Factors predisposing to microbial pathogenicity
• Types of infectious disease

3. Introduction
• Infection and immunity involve interaction between the animal body (host) and the infecting
microorganism .
• Based on their relationship to their hosts,microorganisms can be classified to their hosts,
microorganism can be classified as saprophytes and parasites.
• Saprophytes : are free living microbes that subsisit on dead or decaying organic matter They
are found in soil and water and play an important role in the degradation lof organic materials
in nature. They are generally incapable of multiplying on living tissues and therefore are of little
relevance in infectious disease. Exceptionally , however some saprophytes like B. subtilis may
infect devitalized hosts whose natural resistance is greatly reduce ( opportunistic infection)

4. • THE INITIAL RECOGNITION OF THE ACQUIRED IMMUNOdeficiency syndrome (AIDS) was made by the
recognition of opportunistic infections Opportunistic infections are the ‘AIDS-defining’ event in
approximately 75% of cases and eventually occur in virtually all AIDS patients. Eight opportunistic
infections occur with high frequency in HIV-infected individuals

5. Opportunistic infection AIDS-defining event (%) Ultimate prevalence (%)
Pneumocystis
carinii pneumonia
65 85
Oral and esophagel 6 ?80
Mucocutaneous herpes
infection
2 60
Herpes zoster N/A ?
Mycobacterium
infection
1–2 50
Cytomegalovirus disease 2 10
Cerebral toxoplasmosis 3 10
Cryptococcosis 2 5–13
TABLE 1
Common opportunistic infections in HIV-infected individuals

7. Immunodeficiency disorders
• Key points
• Immunodeficiency disorders disrupt your body’s ability to defend itself against bacteria, viruses,
and parasites.
• There are two types of immunodeficiency disorders: those you are born with (primary), and
those that are acquired (secondary).
• Anything that weakens your immune system can lead to a secondary immunodeficiency
disorder.

8. • Your immune system includes the following organs:
• spleen
• tonsils
• bone marrow
• lymph nodes

9. These organs make and release lymphocytes. These are white blood cells classified as B cells and T
cells. B and T cells fight invaders called antigens. B cells release antibodies specific to the disease
your body detects. T cells destroy foreign or abnormal cells.

10. structures of the functions of the
immune system
• The lymphoid system:
Central ( primary ) lymphoid organs
Thymus
Bone marrow
Peripheral ( secondary ) lymphoid organs
Lymph nodes
Spleen
Cells of the lymphoreticular system:
Lymphocytes

12. Haemopoietic stem cell
• Myeloid progenitor:
• Granulocyte – monocyte progenitor -1) neutrophil 2) monocyte- macrophage
• Eosinophil progenitor- eosinophil
• Basophil progenitor- basophil
• Megakaryocyte-platelets
• Erythroid progenitor- erythrocyte

13. • Lymphoid progenitor:
Natural killer ( nk ) cell
T cell progenitor- 1) T helper cell,2) t cytotoxic cell
B cell progenitor- B cell
Dendritic cell

14. Introduction
• The lymphoreticular system is a complex organization of cell of diverse morphology distributed
widely in different organs and tissues of the body responsible for different organs and tissues of
the body responsible for immunity . Lymphoreticular cells consist of the lymphoid and
reticuloendothelial components , with clearly demarcated functions . The lymphoid cells-
lymphocytes and plasma cells – are primarily concerned with specific immune response . The
phagocytic stem cells , form part of the reticuloendothelial system are primarily concerned with
the scavenger functions of eliminating effete cells and foreign particles . They contribute to non
specific immunity by removing microorganism from blood and tissues. They also play a role in
specific immunity , in afferent and efferent limbs of the immune response.

15. Types of immune response
• The functional anatomy of the lymphoid system can be appreciated on the basis of two types of
immune response to an antigen.
• 1) Humoral immunity : ( antibody mediated , AMI) ,
• It is mediated by antibodies produced by plasma cells are present in blood and other body
fluids ( hence the name ‘ humoral ‘ from ‘ humour’ the old term for body fluids)
• 2) cellular immunity : it is mediated by sensitized lymphocytes

16. Lymphoid system
• The lymphoid system consist of lymphoid organs and cells . The thymus and bone marrow are
the primary lymphoid organs ; the spleen and lymph nodes are the secondary lymphoid organs .
The lymphoid cells consists of lymphocytes and plasma cells .
• Lymphoid cells
- Lymphocytes
- Plasma cells

17. Central ( primary ) lymphoid organs)
• Thymus:
The thymus performs the important function of generating and selecting a repertoire of T CELLs
that will protect the body from infection . In humans , the thymus reaches its maximal relative size
just before birth . It continues to grow till about the twelfth year . After puberty, it undergoes
spontaneous progressive involution ,indicating that it functions best in early life .
Structure: the thymus is located behind the upper part of the sternum . It has two lobes
surrounded by a fibrous capsule . Septa arising from the capsule divide thde gland into lobules
which are differentiated into an outer cortex and an innermedulla . The cortex is crowded with
actively proliferating small lymphocytes . The medulla consist mainly of epithelial cells and
mature lymphocytes , in the middle of which are hassal’s corpuscles , which are whorl –like
aggregations of epithelial cells .

18. Functions
• The primary function of the thymus is the production of the thymic lymphocytes, it is the main site for
lymphocyte proliferation in the body . However , mof the lymphocytes proliferation in the body .
However , of the lymphocytes produced, only about one percent leave the thymus . The rest are ,
destroyed locally. During thymic sele ction as thymocytes develop , some T cells with receptor are
capable of recognizing the antigen – MHC complexes and those that react with self antigen –MHC
and may cause auto immune disease.
• More than 95% of all thymocytes die by by apoptosis in the thymus without ever reaching maturity .
In the thymus , the lymphocytes acquire new surface antigens ( thy antigens) . Lymphocytes
conditioned in the thymus are called Thymus T dependent lymphocytes ‘ or T cells . Unlike in the
peripheral organs , lymphocytes proliferation in the thymus is not dependent on antigenic
stimulation . In fact, peripheral antigenic stimuli do not lead to any immune response in the thymus.
Antigen introduced directly into the thymus may lead to a local immune response . In the thymus ,
they are educated to become capable of mounting cell- mediated immune response against
appropriate antigens.

19. Clinical significance
• Digeorge syndrome: deficient CMI is seen in congenital aplasia , of thethymus in human
beings ( DIGEORGE SYNDROME)
• RUNT disease: deficiency of CMI is evident from lymphopenia deficient graft rejection and the
do called runt disease seen in neonatally thymectomized
• Post thymectomy: T LYMPHOCYTES are selective seeded into certain sites in the peripheral
lymphatic tissue, being found in the white pulp of the spleen , around the central arterioles and
in the paracortical areas of lymph nodes . The regions have been termed thymus ,

20. Bone marrow
• In humans , and other mammals , the bone marrow is the site of B cell origin and development .
Immature B cells originating from lymphoid progenitors proliferate and differentiate , within the
bone marrow with the help of cytokines, inBirds, the bursa of Fabricius is the primary site for B
cell maturation , equivalent to the bone marrow . A selection process within the bone marrow
eliminates B cells with self reactive antibody receptors as in thymic selection during T cell
maturation . All lymphocytes originate in the bone marrow . While T lymphocytes develop in the
thymus , B lymphocytes develop in the thymus , B lymphocytes develop in the bone marrow
itself, in the human foetus , peyer’s patches develop and lymphoid cells and lymphoid cells
appear in the spleen, and lymph nodes by the 20th week of gestation . From then on the foetus
is able to produce IgM and igD . It receives maternal igG , but IgG level fails steadily to reach
minimum levels by the third month. igG production then picks up and becomes adequate , by
2- 3 years . Full immunocompetence is attained only after the first decade of life.

21. Peripheral ( secondary lymphoid organs)
• Lymph nodes : lymph nodes are placed along the course of lymphatic vessels and differentiated
into an outer cortex and an inner medulla . In the cortex are accumulations of lymphocytes (
primary lymphoid follicles ) within which germinal centres ( secondary follicles ) develop during
antigenic stimulation . The follicles contain, besides proliferating lymphocytes , dendritic
macrophages which capture and process the antigen. In the medulla , the lymphocytes , plasma
cells, and macrophages are arranged as elongated branching bands ( medullary cords ) . The
cortical follicles and medullary cords contain B – lymphocytes and constitute the bursa –
dependent areas . Between the cortical following and medullary cords , there is a broad , ill-
defined intermediate zone , ( paracortical area) which contains T lymphocytes , and
interdigitating cells. This constitute the thymus – dependent area. The accumulations of
lymphocytes and interdigitating cells, this constitutes the thymus- dependent area , the
accumulation of lymphocytes ( B and T ) , dendritic macrophages , plasma cells , and
interdigitating dendritic cells in different parts are

23. Functions
the lymph nodes act as a filter for lymph each group of nodes draining as a specific part of the
body. They phagocytosis foreign materials including microorganisms . They help in the
proliferation and circulation of B AND T CELLS . THEY Enlarge following local antigenic
stimulation .

24. Clinical significance
• The effects of splenectomy on the immune response depend on the age . In children ,
splenectomy often leads to increased incidence of bacterial sepsis caused primarily by
streptococcus pneumoniae , Neisseria meningitidis and haemophilus influenzae . In adults , the
effects are less adverse and may lead to bacterial infection ( bacteremia).

25. Mucosa associated lymphoid tissue
(MALT)
• The mucosa lining the alimentary , respiratory , genitourinary and other lumina and surfaces are
constantly exposed to numerous antigens . These areas are endowed with a rich collection of
lymphoid cells , either specialized aggregates like peyer’s patches or scattered isolated lymphoid
tissue (MALT) . Such lymphoid tissues in the gut , from the adenoids and tonsils to the follicles in the
colon are called the GUT Associated lymphoid tissue ( GALT) and those in the respiratory tract , the
bronchus associated lymphoid tissue(BALT) .
• MALT contains lymphoid as well as phagocytic cells, MALT has functional significance
in the body’s defence due to it’s large populations of antibody – producing plasma cells
Than that of plasma cells in the spleen, lymphnodes and bone marrow. Both BAND T cells are present
. While the predominant immunoglobulin produced in the mucosa is secretory IgA , other
immunoglobulin IgG , IgM and IgE are also formed locally. There appears to be free traffic of antigen
– specific effector between the various mucosal and secretory areas , so that antigenic exposure at one
site may cause the production of specific antibody at the other mucosal and secretory sites .

26. Cells of the lymphoreticular system
• Lymphocytes:
Lymphocytes constitute 20-40 percent of the body’s white blood cells and 99% percent
of the cells in the lymph . On the basis of function and cell membrane components
, lymphocytes an be broadly subdivided into three types : B cells , T cells and natural killer cells .
Structure: lymphocytes are small , round cells found in peripheral , blood , lymph, lymphoid
organs, and in many other tissues . The human body contains about 10 power 12 lymphocytes ,
approximately 10 power9 of them being renewed daily, lymphocytes are now recognized as the
main cellular element

27. Immunodeficiency diseases
Definition
• Immunodeficiency disease are conditions where are the defense mechanism of the body are
impaired , leading, to repeated microbial infections of varying severity and sometimes
enhanced susceptibility to malignancies .
• Deficiencies of defense mechanism may involve specific immune functions – humoral immunity,
cell mediated immunity or both – or non specific mechanism such as phagocytosis and
complement , which augment and act in conjuction with specific immune process.

28. The lymphoid system
-Lymphoid cells _
• Lymphocytes
• Plasma cells
- Lymphoid organs
• primary ( central orgams)
- thymus
-bone marrow ( bursa of fabricius)
• Secondary ( peripheral organs)
- Spleen
- Lymph nodes
- Mucosa associated lymphoid tissue (MALT)
- Lymphoid tissue in gut liver, lungs, bone marrow

29. The lymphoid system
• The lymphoid system consist of lymphoid organs and cells. The thymus and bone marrow re the
lymphoid organs ; the spleen, and the lymph nodes are the secondary lymphoid organs. The
lymphoid cells of lymphocytes and plasma cells.
• Central lymphoid ( primary ) lymphoid organs :
• Thymus: he thytmus performs the importance function of generating and selecting a repertoire of t
cells that will protect the body from infection. In humans , the thymus reaches its maximal relative size
just before birth, it continues to grow till about the twelfth year, after puberty it undergoes
spontaneous progressive involution,indicating , that it function best in early life.
• Structure: the thymus is located behind the upper part of the sternum . It has two lobes surrounded
by a fibrous capsule , septa arising from the capsule divide the gland into lobules which are
differentiated into an outer cortex and an inner medlla. The cortex is crowded with actively
proliferating small lymphocytes . The cortex is crowded with actively proliferating small lymphocytes .
The medulla consist mainly of epithelial cells and mature lymphocytes in the middle of which are
Hassall’s corpuscle which are whorl like aggregations of epithelial cells.

30. Functions :
• The primary function of the thymus is the production of thymic lymphocytes . It is the main site
for lymphocyte proliferation in the body, however of the lymphocytes produced about, one
percent leave thymus, the rest are destroyed locally ,during thymic selection, as thymocytes
develop, some t cells with receptors are capable of recognizing antigen-MHC complexes, the
thymus induces the death of those tcells that recognize the antigen –MHCcomplexes . More
than 95 percent of all thymocytes die by apoptosis in the thymus without ever reaching
maturity, in the thymus without ever reaching maturity. In the thymus, the lymphocytes, acquire
new surface antigens , lymphocytes conditioned in the thymus are called thymus, dependent
lymphocytes or t cells . Unlike in the peripheral organs , lymphocyte proliferation in the thymus
is not dependent on antigenic stimulation . In fact , peripheral antigenic stimuli do not lead to
any immune response in the thymus may lead to a local immune response. The thymus confers
immunological competence , on the lymphocytes during their stay in the organ . In the thymus ,
they are educated , to become cpable of mounting cell – mediated immune response against
appropriate antigens .

31. Bone marrow
• In humans and other mammals, the bone marrow is the site of B cell origin and development .
Immature B cell originating from lymphoid progenitors proliferate and the differentiate within
the bone marrow , with the help of cyto kines , in birds the bursa of fabricious is the primary site
for b cell maturation , equivalent, to the bone marrow
a selection , process within the bone marrow eliminates , B cells with self reactive antibody
receptors, as in thymic selection , during T cell maturation . All lymphocytes, originate in the bone
marrow. While t lymphocyte originate in the bone marrow, while T lymphocyte develops in the
thymus B lymphocytes develop in the bone marrow itself . In the human foetus, peyer’s patches
develop and lymphoid cell appear in the spleen , and lymph nodes by the 20th week of gestation ,
from there on the foetus is able to reproduce IgM and Ig D . It receives maternal IgG , but IgA
and IgE are not present . At birth , Ig M production is enhanced but the IgG level falls , steadily to
rach minimum levels by the third month. IgG production then picks up and becomes adequate by
2- 3 years . Full immunocompetence is attained only after the first decade life.

32. Clinical significance
• Digeorge syndrome : deficient CMI is seen in congenital aplasia of the thymus in human being (
digeorge syndrome) ,
• Runt disease : deficiency of CMI is evident from lymphopenia , deficient graft rejection and the
so called

34. Peripheral ( secondary ) lymphoid
organs

35. Cells of the lymphoreticular system
• Lymphocytes: lymphocytes constitute 20-40 percent of the body white blood cell and 99
percent of the cells in the lymph. On the basis of function and cell membrane components ,
lymphocytes can be broadly subdivided into three types B CELLS, TCELLS, AND NATURAL KILLER
CELLS.
• STRUCTURE: lymphocytes are small, round cells, found in peripheral blood lymph , lymphoid
organs, and in many other tissues . The human body contains about 10 to power 12
lumphocytes , approximately 10 to power 9 of them being renewed daily.
• Classification: depending on their life span , they can be classified as short lived and long lived
lymphocytes . In humans , the short lived lymphocytes have a life span of about two weeks ,

36. Cells of

38. Immune response
• Humoral immune response ( antibody mediated)
• Primary and secondary responses
• Cellular immune response:
Introduction of cell mediated immunity
Cytokines
Theories of immune response

39. Introduction
• The specific reactivity induced in ahost by an antigenic stimuli is known as the immune respone .
• The immune response can be of two types : humoral (antibody –mediated) and cellular ( cell
mediated) . The two are are usually developed together , though at times one , or the other
may be predominant or exclusive , they usually act in conjunction , but sometimes in opposition.

40. Antigen presenting cells
• There are two types of antigen presenting cells in the body.
• Macrophages
• Dendritic cells
• 1) macrophages : - the macrophages are the large phagocytic cells, which digest the invading
organism to , to release the antigen , the macrophages are present along with lymphocytes , in
almost all the lymphoid tissue .
• 2) dendritic cells :- the dendriti cells are nonphagocytic in nature , three types of dendritic cells
are involved in this ,
• I) dendritic cells in spleen , which traps the antigen in blood,
• Ii) follicular dendritic cells in lymph nodes , which trap the antigen in the lymph and,
• Iii) langerhan’s dendritic cells in skin, which trap the organisms coming in contact , with body
surfaces.

41. • Role of antigen presenting cells: these dendritic cells are nonphagocytic in nature, three types
or denritic cells are involved in this,
• i) dendritic cells in spleen, which trap the antigen in blood
• I) follicular dendritic cells in lymph nodes ,which trap the antigen in theb lymph.
• Ii) langerhan’s cells in skin, traps the organisms , coming in contact with body surfaces.
• Site of er

42. Role of antigen presenting cells
• When foreign organisms invde the body, the macrophages or other antigen presenting , cells ,
kills, them mostly by mens of phagocytes . Later , the antigen from the organisms is digested ,
into polypeptides , the polypeptides, products are presented to T lymphocytes ( and also B
lymphocytes ) along with human leukocyte antigens ( HLA’s ) . HLSA’s are the molecules ,
arranged , inseries in the genes located in short arm of chromosome 6 . The cluster of genes
with HLA’s re the molecules arranged in series in the genes with HLA is called MAJOR
HISTOCOMPATIBILITY COMPLEX , (MHC) . HLA’s are easily recognized by the cells of immune
system and hence, the name a ntigen is given to them.
• Now the antigenic products activate the help[er T cells and B lymphocytes . The macrophages
also secrete some substance called interleukin 1, this causes activation , and proliferation of
lymphocytes.

43. Role of helper T cells
Helper T cells help in promoting various activities of immune system, activated by the antigenic, products of
foreign body the helper T cells stimulate the other T cells and the B cells.
There are two types of helper T cells called ,T helper ( TH1) cells, and T helper TH2 cells.
Role of TH1 cells : TH1 helper cells are concerned with cellular immunity . These helper T cells secrete interleukin 2
and gamma interferon, interleukin2 activates the other T cells . Gamma interfron interleukin 2 activates promotes
phagocytic actionof cytotoxoic cells. Macrophagesand natural killer cells.
Role OF TH2:
TH2 cells are concerned with humour immunity and secrete interleukin 4 and interleukin 5 , these are
interleukins are concerned with it.

44. Role of cytotoxic cells
• The activated cytotoxic T cells circulate through blood lymph and lymphatic tissues and destroy
thev invading organisms by attacking them directly .
• Mechanisms of action of cytotoxic T cells:
The outer membrane cytotoxic T cells contains somes receptor proteins . Thesecreceptor
proteins bind the antigens or organisms tightly with cytotoxic cells . Then the T cells are enlarged
and release cytotoxic substances like the lysosomal enzymes . These substance destroy the
invaded organisms . Like this , each killercell can destroy a large number of microorganisms one
after another.
Other action of cytotoxic T cells:
1) The cytotoxic T cells also destroy cancer cells , transplanted cells like those of te

45. Role of plasma cells
• The B lymphocytes are proliferated andtransformed into two types of cells namely, plasma cells
and memory cells . The plasma cells produce the antibodies which are globulin in nature . The
antibodies are called immunoglobulins in nature, thantibodies ,
The rate of antibody production is very high , that is each plasma cell produces , the antibodies
are released into lymph and then transported into the circulation . The antibodies are produced
until the end of lifespan of each plasma cells that is from several days to several weeks.
Role of memory B cells : some of the B lymphocytes activated by the antigen are transformed
into memory B cells , which occupy the lymphoid tissues throughout the body , the memory cells
are in active until the body is exposed to the same organisms for the second time.

46. • During the second exposure the memory cells are stimulated by the antigen and produce more
quality of antibodies at a faster rate, than in first exposure . The antibodies produced during the
second exposure to the foreign antigen are also more potent than those produced during first
exposure. The forms the basic principles of vaccination against the infections.

47. • Role of helper T cells:
• Helper Tcells are simultaneously activated by the antigen , the activated helper T cells secrete
two substances called interleukin 2

48. Immunohaematology
• Introduction
Blood was considered the essence of life and was believed to cure diverse diseases and restore youth
and vitality to aged. Blood transfusion became scientific feasible only after the discovery of blood
groups.
History:
In his original experiment , Landsteiner ( 1900 ) cross tested serum from himself and five of his
colleagues against red blood cells . Three distict patterns of agglutination were observed.
Cells which failed to agglitinate groupO , while cells agglutinating in the two different patterns were
called groups A and B respectively. The fourth group AB was described later by his pupils VON
DECASTALLO AND STURLI( 1902) . IN 1930 , Landsteiner was awarded the nobel prize for his discovery
of human blood groups.
The ABO system is the most important of all blood group systems and its discovery made blood
transfusion possible.

49. • ABO BLOOD GROUP SYSTEM
• The ABO system contains is the most important of all blood group systems and its discovery
made blood transfusion possible.
• The ABO system contains four blood groups and is determined by the presence or absence of
two distinct antigens, A andB on the surface of erythrocytes.
• The four groups are also distinguished by the presence or absence of two distinct isoantibodies
in the serum. The serum contains the isoantibodies specific for the antigen that is absent in red
cell. The serum contains the isoantibodies specific for the antigen that is absent in the red cell.
The serumof a groupA individual has anti –B antibody , group B has anti A and group O both
anti-B anti- A are absent .
• Blood

50. Classification
• Primary immunodeficiencies result from abnormality in the development of immune
mechanism.
• Secondary immunodeficiencies- are consequences of disease are , drugs, nutritional
inadequacies and other process that interfere with proper functioning of the mature immune
system