Immunochemistry involves the study of the molecular mechanisms of the immune system, especially antibodies, antigens, and their interactions. The document defines innate and active/passive immunity. Innate immunity refers to nonspecific defenses like skin, chemicals, and immune cells that attack foreign cells. Active immunity results from antibody production when exposed to an antigen, while passive immunity involves the transfer of readymade antibodies. The mechanisms of the immune system include physical barriers, chemicals, blood cells, macrophages, inflammation, fever, interferons, natural killer cells, and the complement system.

1. IMMUNOCHEMISTRY
RATHEESH R L

2. DEFINITION
Immunochemistry is a branch of chemistry that
involves the study of the molecular mechanisms
underlying the function of the immune system,
especially the nature of antibodies, antigens and
their interactions.

3. IMMUNITY
• It is defined as the resistance offered by the
host to toxic molecules, micro organisms and
foreign body.

4. TYPES OF IMMUNITY

5. INNATE IMMUNITY
• Innate immunity refers to nonspecific defense
mechanisms and is basic immunity which may be
genetically passed from one generation to next
generation.
• These mechanisms include physical barriers such
as skin, chemicals in the blood, and
immune system cells that attack foreign cells in
the body.

6. It may be,
• Species immunity
– Individuals in the same species exhibit uniform
pattern of susceptibility to different infections.
• Racial immunity
– Within one species, different races shows
difference in resistance.
• Individual immunity
– Different individuals of the same species and races
show variation to infection.

7. FACTORS AFFECTING IMMUNITY
• AGE
• NUTRITION
• HORMONAL INFLUENCES

8. MECHANISM
The innate immunity acts in two levels
1.Epithelial surface level
2. Chemical secretions
3. Cellular factors

9. Epithelial surface level
• Skin
– Sebaceous glands secrete sebum which contains
both saturated and unsaturated fatty acids and
they kills the micro organism
• Conjunctiva
– Lysozyme which is present in the tear acts against
the micro organism
• Nose, naso pharynx and respiratory tract
– The mucus present in the respiratory tract will
absorb all the dust particles and preventing the
entrance to lungs.

10. • Mouth, stomach and intestinal tract:
– Saliva secreted by the salivary gland had a mild
bactericidal action.
– In stomach the high acidity will prevent the
growth of micro organism.

11. Chemical secretions
• The oil and sweat produced by skin glands
contains fatty acid and lactic acid which are
bactericidal in action.
• Lysozymes present in sweat and tears
contribute antibacterial activity.
• HCL of stomach, properdin, leukins and beta
lysine like substances present in serum have
the same bactericidal action.

12. Cellular factors
• Blood cells
• Macrophages
• Inflammatory reaction
• Fever
• Interferons
• Natural killer cells
• Complement system

13. Blood cells
• White blood cells (WBCs), also called leukocytes or
leucocytes, are the cells of the immune system that
are involved in protecting the body against both
infectious disease and foreign invaders.
• Neutrophils performs phagocytosis and destroy
micro organisms.
• Basophils release histamine that plays a role in
inflammatory reaction.

14. • Monocytes of blood changes to macrophages
at the time of infection and shows phagocytic
action.

15. Macrophages
• Macrophages are the transformed forms of
monocytes. Later they are increasing in size,
and destroys the foreign particles by
phagocytosis.

16. Inflammatory reaction
• Incase of cuts, wounds and injuries the
microbes get entered to the body.
• These microbes release certain chemicals in
the body.
• The basophils release histamin and causes the
dialation of capillaries in the affected area and
increases their permeability.
• As a result more blood rushed to the affected
area and imparts it warmth and redness.

17. • The plasma leaks to the affected tissue spaces
and dialutes the toxin released by the
microbes and decreases their toxicity.

18. fever
• The mechanism of fever appears to be a
defensive reaction by the body
against infectious disease.
• When bacteria or viruses invade the body and
cause tissue injury, one of the immune
system’s responses is to produce pyrogens.
• These chemicals are carried by the blood to
the brain, where they disturb the functioning
of the hypothalamus, the part of the brain
that regulates body temperature.

19. • The pyrogens inhibit heat-sensing neurons and excite cold-
sensing ones, and the altering of these temperature sensors
deceives the hypothalamus into thinking the body is cooler
than it actually is.
• In response the hypothalamus raises the body’s temperature
above the normal range, thereby causing a fever. The above-
normal temperatures are thought to help defend against
microbial invasion because they stimulate the motion,
activity, and multiplication of white blood cells and increase
the production of antibodies.

20. • At the same time, elevated heat levels may
directly kill or inhibit the growth of some
bacteria and viruses that can tolerate only a
narrow temperature range.

21. interferons
• In case of viral infections, the cells invaded by
a virus produces an antiviral protein called
interferons.
• The interferons make the neighbouring cells
resistant against viral infections.

22. Natural killer cells
• These are the type of lymphocytes which kills
the infected cells and checks the spread of
infection.

23. Complement system
• It is a system of 30 proteins present in the
serum. These proteins defend the body by
different ways, like by strengthening
phagocytic and inflammatory reactions and by
rupturing the cell membranes of the
microbes.

24. ACTIVE IMMUNITY
• The immunity which results from the production
of antibodies by the immune system in response
to the presence of an antigen.
• Its of two types
– Natural active immunity
– Artificial active immunity

25. Natural active immunity
• When there is repeated exposure to a specific
type of micro organism the resistance will
develop against the organism and is called as
Natural active immunity

26. artificial active immunity
• It’s the immunity that is mainly acquired
through the vaccination method.

27. PASSIVE IMMUNITY
• It’s the immunity that is induced in the
persons body by the transfer of readymade
antibodies against infective agents.
• It may also be,
– Natural passive immunity
– Artificial passive immunity

28. Natural passive immunity
• It’s the resistance passively transferred from
mother to fetus through placenta.
• IgG antibodies can cross the placental barrier
to reach the fetus.

29. Artificial passive immunity
• It’s the resistance passively transferred to
recipient by the parenteral administration of
antibodies.

30. MECHANISM
• This mechanism defends the body against
specific micro organisms by the activation of
immune system.

31. Events..
• Cells of the immune system:
– Lymphocytes: the T- lymphocytes and B-
lymphocytes are the basis of immune system.
– Antigen presenting cells: these are the specialized
cells which includes macrophages.

32. • Types of immune system:
– Humoral immunity, also called the antibody-
mediated immune system, is the aspect
of immunity that is mediated by macro molecules
found in extracellular fluids such as secreted
antibodies, complement proteins, and certain
antimicrobial peptides.

33. – Cell mediated immunity: Cell mediated
immunity is an immune response that does not
involve antibodies, but rather involves the
activation of phagocytes and antigen-specific
cytotoxic T-lymphocytes.

34. • Types of immune response:
– Primary immune response: when the body comes
in contact with an antigen for the first time, the
response is called Primary immune response.
– Secondary immune response: it occurs when body
comes in contact with the same antigen again.