Immune System

“Disease” is a very wide term. Any change from the normal state that causes discomfort or disability or impairs the health may be called a disease. The oxford English Dictionary defines disease as “a condition of the body or some part or organ of the body in which its functions are disturbed or deranged”.  A person free of disease is often said to be healthy. This is not fully true. The term “Health” has a very wide scope. The World Health Organization (WHO) gave the following definition of health in 1948

TYPES OF DISEASES

The diseases may be broadly classified into two types : Congenital and acquired.

(i) Congenital Diseases : These are anatomical or physiological abnormalities present from birth. They may be caused by (i) a single gene mutation (alkaptonuria, phenylketonuria, albinism, sickle-cell anaemia, haemophilia, colour blindness); (ii) chromosomal aberrations (Down’s syndrome, Klinefelter’s syndrome, Turner’s syndrome); or (iii) environmental factors (cleft palate, harelip). Unlike the gene-and chromosome-induced congenital defects, environmentally caused abnormalities are not transmitted to the children.

(ii) Acquired Diseases : These diseases develop after birth. They are further of two types : communicable and non-communicable.

(a) Communicable (Infectious) Diseases : These diseases are caused by viruses, rickettsias, bacteria, fungi, protozoans and worms.

(b) Noncommunicable (Noninfectious) Diseases : These diseases remain confined to the person who develops them and do not spread to others.

                                                              VIRUS COMMUNICABLE DISEASES

                                                                         Bacterial diseases and their pathogens

Disease	Causative Bacterium
Cholera Pneumonia Typhoid Tetanus Diphtheria Whooping cough Tuberculosis Plague Leprosy Syphilis Gonorrhoea Diarrhoeal Diseases Anthrax	Vibrio comma (Vibrio cholerae) Diplococcus pneumoniae Salmonella typhi Clostridium tetani Corynebacterium diphtheriae Bordetella pertussis Mycobacterium tuberculosis Pasteurella pestis Mycobacterium leprae Treponema pallidium Neisseria gonorrhoeae Escherichia coli, Shigella dysenteriae, Campylobacter, Salmonella Bacillus anthracis

PROTOZOAN COMMUNICABLE DISEASES

                                                                   Sexually Transmitted Diseases (STD) in Human

Disease	Causative organism	Nature of Disease	Symptoms – Treatment
(1)AIDS (Acquired Immuno deficiency Syndrome)	Retrovirus – HIV	Viral	Enlarged lymph nodes, long fever, weight loss – Nil
(2)Genital Herpes	Herpes simplex virus	Viral	Painful ulcer on genitals – Nil
(3)Genital warts	Human papilloma virus (HPVs)	Viral	Tumor of the vulva, vagina, anus and penis – Nil
(4)Gonorrhoea	Neisseria gonoerrheae	Bacterial	Infection of all genital organs or PID – Penicillin
(5)Chlamydiasis	Chlamydia trachomatis	Bacterial	White patches on vagina or PID – Nystatin
(6)Syphilis	Treponema pallidum	Bacterial	Cancer and skin eruption – Benzene and Penicillin
(7)Trichomoniasis	Trichomonas vaginalis	Protozoan	Greenish-yellow vaginal discharge–Metronidazole.
(8)Chancroid	Haemophilus ducreyi		Foul discharge and ulcer Drug : Sulphonamide
(9)Lymphogranuloma venerum	Lymphogranuloma psittacosis bacteria		Inguinal lymphadenopathy Drug : Tetracycline

Common name	Zoological name	Causative organism	Disease
Mosquitoes	Anopheles sps Culicine sps Stegomyia sps Aedes aegypti	Plasmodium Wuchereria bancrofti Flavovirus fibricus Dengue virus	Malaria
Rat flea	Xenopsilla cheopsis Xenopsilla sps	Pasteurella pestis R. typhi	Bubonic plague Endemic typhus
Flies	Musca sps	Shigella sps Salmonella typhi Salmonella paratyphi Hepatitis type – A virus	Bacillary dysentery Typhoid fever Paratyphoid fever Infectious hepatitis
Sand fly	Phlebotomus papatasi Phlebotomus	virus Leishmania donovani	Sand fly fever Kala azar
Body louse	Pediculus	Rickettsia prowazeki R. Quintana	Trench fever
Mite	Trombicula akamushi	R. Tsutsugamushi	Scrub typhus (Tsutsugamushi fever)
Itch mite	Sarcoptes scabieri	–	Scabies
Tick fever,	Amblyomma sps	R. rickettsiae	Rocky mountain spotted theileriosis
House fly	Musca domestica	Vibrio cholerae E.coli	Cholera Infantile diarrhoea
Bed bug	Cimex	–	Relapsing fever
Tse-tse fly	Glossina palpalis	Trypanosoma gambiense	Sleeping sickness

                                                                        Important Helminth Diseases in Humans

Disease	Pathogen	Habitat	Mode of Infection
Taeniasis & Cysticercosis	Taenia solium – the pork tapeworm	Intestine	By taking raw or undercooked measly pork
Ascariasis	Ascaris lumbricoides	Small intestine	By taking eggs with food and water
Filariasis (Elephantiasis)	Wuchereria bancrofti – the flarial worm	Lymphatics and connective tissue	By bites of Culex mosquitoes
Ancylostomiasis (Hookworm disease)	Ancylostoma duodenale – the hookworm	Small intestine	By boring through the skin, usually of feet.

IMMUNE SYSTEM

System of body which prevent the body fromdiseases and cancer is calledimmune system.
(L. immunis – freedom/exempt).

IMMUNITY

• Resistance of the body against a pathogen or disease. Immunity is the ability of an individual to resist against diseases and allergy.

• Immune system protects body from various pathogens/infectious agents/ allergens and cancer.

• Immunology is the science of development of immunity against particular pathogen / allergens.

TYPES OF IMMUNITY

Immunity is of two types –

(1)Congenital immunity or innate Immunity or Non-specific immunity.

(2)Acquired immunity or Adaptive or specific immunity.

CONGENITAL / INNATE / INBORN / NONSPECIFIC IMMUNITY

It ispresent by birth in most of animals and forms natural defence system which is always available to protect the body against various types of antigens. It is also callednative immunity.

ACQUIRED /ADAPTIVE / SPECIFIC IMMUNITY

• This immunity isacquired after birth due to previous infection, vaccination or inoculation of antiserum. It occurs only in vertebrates.

• It supplements protection provided by innate immunity. This immunity recogniseas and selectively eliminate the pathogen.

• It has four unique features –

(i)Specificity

·Acquired immunity is specific for specific micro-organisms.

It is the ability to differentiate various foreign molecules.

(ii)Diversity

·This system recognise the vast variety of micro-organisms.

(iii)Discrimination between self and non-self

·It can recognise self (body or tissue) and non self (foreign tissue) and respond according to them.

(iv)Memory

·When a pathogen enter inside the body, body takes longer times to recoganise and respond to it, this is calledprimary immune response but the memory of this encounter remains in immune system.

·When this pathogen enters second time inside the body, body immune system rapidly recognises this pathogen and responds quickly to it. This is calledsecondary immune response. This is based on memory of immune system.

TYPES OF ACQUIRED IMMUNITY

It is of two types – (1) Passive acquired immunity (2) Active acquired immunity.

(1)Active Immunity : When an organism’s own cells produce antibodies it is called active immunity. It develops when a person suffers from a disease or gets vaccination for a disease.

(2)Passive Immunity : In passive immunity, the antibodies are produced in some other organisms (e.g. vertebrates) in response to the given antigen. These antibodies are then injected into the human body at the time of need. This is known asinoculation. For example persons infected by rabies, tetanus, Salmonella (causes food poisoning) and snake venom are given the sufficient amount of antibodies so that they can survive.

                           Difference between Active Immunity and Passive Immunity

Active Immunity	Passive Immunity
(1)It is developed when the person’s own cells produce antibodies in response to infection or vaccine.	(1)It is develop when antibodies produced in other organisms are injected into a person to counter act antigen such as snake venom,
(2)It provides relief only after long period.	(2)It provides immediate relief.
(3)It has no side effects.	(3)It may cause reaction.
(4)It is long lasting.	(4)It is not long lasting.

                                                              Autoimmune Disorders

Disorder	Symptoms	Antibodies Against
Glomerulonephritis	Lower back pain	Kidney cell antigens that resemble Strep bacteria antigens
Grave disease	Restilessness,Weight loss,irritability, Increased heart rate  and Blood pressure	Thyroid gland antigens near thyroid stimulating hormone receptor, causing overactivity
Juvenile diabetes	Thirst, hunger, weakness, emaciation	Pancreatic beta cells
Hemolytic anemia	Fatigue and weakness	Red blood cells
Myasthenia gravis	Muscle weakness	Receptors for nerve messages on skeletal muscle
Pernicious anemia	Fatigue and weakness	Binding site for vitamin B on cells lining stomach
Rheumatic fever	Weakness, shortness of breath	Heart cell antigens that resemble Strep bacteria antigens
Rheumatoid arthritis	Joint pain and deformity	Cells lining joints
Scleroderma	Thick, hard, pigmented skin patches	Connective tissue cells
Systemaic lupus erythamtosus	Red rash on face, prolonged fever, weakness, kidney damage	DNA, neurons, blood cells
Ulcerative colitis	Lower abdominal pain	Colon cells

                                                           Cells of Immune System

S.No.	Cell Type	Function
	Helper T Cell	Assists the immune process by helping other cells in the immune system to achieve an efficient immune response.
	Cytotoxic T Cell	Detects and kills infected body cells recruited by helper T cells.
	Suppressor T Cell	Guards against the overproduction of antibodies and overactivity of cytotoxic T cells.
	Memory cell	“Remembers” the original stimulation by the immune system and remains in the lymphoid tissue.
	Natural killer cell (NK)	The lymphocyte without receptor site and help to attack and neutralize virus-infected and tumor cells.
	B Cell	Precursor of plasma cell, specialized to recognize a specific foreign antigen.
	Plasma cell	Biochemical factory devoted to the production of antibodies directed against a specific antigen.
	Mast cell	Initiator of the inflammatory response which aids the arrival of leucocytes at a site of infection, secretes histamine and is important in allergic response.
	Monocyte	Precursor of macrophage.
	Macrophage	The body’s first cellular line of defence; also serves as antigen presenting cell to B and T cells and engulfs antibody covered cells.

                                                                                      Some Important Vaccines

Name of Vaccine	Category of Vaccine	Used for treatment of
(1)B.C.G.	Live vaccine (actual weakened germs)	Tuberculosis
(2)Cholera Vaccine	Killed vaccines (micro-organisms are killed)	Cholera
(3)Mumps Vaccine (MMR)	Live vaccine (actual weakened germs)	Mumps Measles & Rubella
(4)Oral Polio Vaccine (OPV)	Live vaccine	Polio, 1st does given when child is 3 months old. Booster does is given after 1 year
(5)Rubella Vaccine	Live vaccine	German measles and small pox
(6)Rubeolla Vaccine	Live vaccine	Measles
(7)Tetanustoxoid (TT)	Toxoid (bacterial toxin looses toxicity but retains antigenicity)	Tetanus
(8)Toxoid Serum	Toxoid (bacterial toxin looses toxicity but retains antigenicity)	Diphtheria
(9)Typhoid Vaccine (TAB)	Killed vaccine (micro organisms are killed)	Typhoid (Typhoid & Paratyphoid)
(10) Triple Antigen (DPT) (Diphtheria, Pertussis Tetanus)	Toxoid	Diphtheria, tetanus and whooping cough, Ist dose given when child is 3 months old. Booster dose at 2 years.

• Alesis Carr : Proposed “Principle of Histocompatibility”.

• Two types of antigens involved in rejection of organ transplantation :

• • Major Histocompatible complex antigens (Human Leucocyte Antigens) : Present on the surface of the cells of transplanted organs.

  • Minor histocompatible antigens.   

• Immuno suppressants : Drugs used to suppress the immune system to avoid the rejection of organ transplantation.

• Sibling species : Individuals have more or less similar genetic constitution.

• Dr. Gait inventor : Developed the technique of tissue engineering.

• Dermograft : It involves human skin graft. It is first achievement in the field of tissue engineering and may lead a new era in the field of transplant surgery. In this, stem cells are taken from the foreskin of newly circumcised body and then grown on a biodegradable mesh.

• Colostrum : First milk secreted from the mammary glands after birth of baby.

• Anamnestic response : Elevated immune response caused by memory cells to an antigen exposed for the second time.

• Antiserum : Serum containing antibodies against a specific antigen.

• Autograft : Transplantation of tissue from one part of body to another part of same individual.

• Homograft or Allograft : A graft derived from a genetically dissimilar individual of same species.

• Heterograft or Xenograft : A grafted between organisms of different species.

• Hepatitis-A is also known as infectious hepatitis and is caused by HAV.

• Hepatitis-D is caused byHepatitis-D Virus (HDV).

• Viricides : Virus- killing agents.

• Hepatitis-A  andE spread through consumption of contaminated food, milk, drinks, juices and water.

• Former Baywatch beautyPamela Anderson has contracted the potentially fatal liver disease hepatitis-C by sharing a tattoo needle with her ex-husband Tommy Lee.

• Brachytherapy : A special radiotherapeutical technique in which a very high doze of radiation is given to small volume of body tissues in short period from small radioactive sources like Radium, Cobalt-60, Iridium - 192, etc. Another advanced technique of radiation therapy of cancer isIntensity Modulation Radiotherapy (IMRT) in which non-uniform beams are fired on the affected organ from several angles to deliver desired doses to the tumour while minimising dose to surrounding organs.

• Adjuvant vhemotherapy is the technique of using several drugs at the same time.

• Monoclonal antibodies and interferous have been used against leukaemia, lymphosarcoma and breast cancers.

• Leukemias are three types :Lymphocytic leukemia (increase in number lymphocytes, enlargement of lymph nodes, etc.);Granulocyotic leukemia andMonocytic Leukemia.  

• Autoimmune diseases are kind of degenerative diseases as these involvedestouction of certain body cells.

• Certain latest informations about AIDS :

• • AIDS - virus is a retro-virus so multiplies by the process of reverse transcription.

  • HIV has high mutability.