Lesson - 4 immunity and blood group


Immunity :- 

  1. This is the power of body which is provides resistance against pathogens and disease caused agent.
  2. In every day we encounter with many pathogens, but it does not suffer from every disease very easily due to presence of resistance power (immunity) of body.

Immunology :- 

  1. The study of the all reactions and related system that work for all eradication pathogens from body is called immunology.
  2. A large number of cells, lymphatic or immunological organ (lymph nodes, liver, thymus, bone marrow etc.) blood and lymph is functional in this system.
  3. Two types of immunity work in the body.
  • Innate immunity
  • Acquired immunity

Innate immunity :- 

  • This is an inborn immunity system which is also called nonspecific or natural immunity.
  • It is called nonspecific immunity because it is not provide any specific resistance against against any specific pathogens rather it employs a common action against all type of pathogens.
  • The following factors work for innate immunity
1. Physical barrier :- Skin, cilia, flagella found on nesal cavity and mucous and others organs etc.

2. Chemical barrier :- lactic acid is found in vagina, acidic conditions of the stomach, chemical present on the skin, chemical found in secretion of liver, tears, saliva, sweat.

3. Cellular barrier :- Cell like macrophages, monocytes, neutrophils, which are active in phagocytosis. Beside cell like natural killer cells are cellular barrier.

4. Fever, inflammation etc.

Acquired immunity :- 

This is called adaptive immunity or after birth immunity or specific immunity.
In this type of immunity, host specially attacks on specific evaders microorganisms or foreign objects.
Antibodies is form in this type of immunity and this antibodies work against specific microorganisms or foreign objects. These reactions stimulate cell mediated immunity as a result antigen is eliminated from the body.

Specific immunity is two types.

1. Active immunity :- immunity in which body self synthesized antibodies against antigen. This immunity work for that particular antigen which antibodies is synthesized.

2. Passive immunity :- immunity in which specific external antibodies against a particular antigen are introduced in the body. In this immunity antibodies is not synthesized in the body. 
Example - vaccine of tetanus and diphtheria.

Antigen :- 

  1. Those outer substance or pathogens entering in the body activate B - lymphocytes cell to differentiate in antibody secreting plasma cells is called antigen.
  2. Normally they are foreign objects or pathogens which have a molecular weight of 6000 Dalton or more.
  3. They can many various chemical group like protein, polysaccharide, nucleic acid or lipid.
  4. Sometimes some body cell or body substance like infectious cell or cancer cells can also acts as antigen.
  5. After entering antigen in the body, an antigen encounter first innate immunity. Afterwards this antigen active specific immune system.
  6. The whole molecule of antigen does not interaction with antibody so the part of antigen which is interact with antibody is called "The antigen determinant or epitope" 
  7. In a protein, a chain of 6 - 8 amino acid is react as epitope.
  8. The total number of epitope is called valence of antigen. Valence of a bacterial antigen is 100 and more.
The destruction of antigen by specific immunity is carried out in four steps. 
1. Differentiation between self and foreign Antigen. 
2. Plasma cell formation by the activated B cells. They are produced on the basis of the epitope(s) present on the foreign antigen. 
3. Synthesis of specific Antibodies by the Plasma cells. 
4. Destruction of the Antigen by Antigen (Ag)-Antibody (Ab) reactions and Cell Mediated Immunity. 

Antibody :- 

  1. Antibodies are also called as Immunoglobulin's (Ig). 
  2. They are Gamma Globulin ( γ globulin) proteins which are synthesized by the Plasma cells and are found in the blood and other body fluids.
  3. Antibodies identify and interact with the antigen to make it ineffective.
  4. The portion of the antibody which interacts with the Antigen is called Paratope. 

Structure of Antibody :- 

         Describe the structure of an antibody.
  1. Antibody has a shape similar to the "Y" alphabet of English.
  2. It is composed of four structural units. 
  3. There are two heavy and large [H] and two light and small [L] polypeptide chains. 
  4. One heavy and one light chain together forms HL dimer. 
  5. Two such [HL] dimers together forms an Antibody.  
  6. In other words an Antibody molecule is made up of two homogeneous halves. 
  7. Both these halves are joined with each other through disulfide bonds.  
  8. Each of the half is made up of one H and one L polypeptide chain. 
  9. The H and L chain found in each of the halves are also joined with disulfide bonds.
  10. Each heavy chain is made up of 440 amino acids while each L chain is made up of 220 amino acids. 
  11. The heavy chain is attached with a carbohydrate moiety. 
  12. The point of origin of the Y structure of most of the Antibodies is flexible and is known as Hinge region. 
  13. Being flexible this region permits the variable portion of the Antibody to adjust according to the size of the antigen and react with it.  
  14. Each heavy and light chain can be divided into two parts - 
  • Variable Portion: This portion reacts with the Antigen and is found on the NH2, end of the chain.  This portion is also called Fab portion. 
  • Constant Portion: This portion is situated at the COOH end of the chain and is also called as Fc portion. 

 Types of Antibodies :- 

  1. Five different types of heavy polypeptide chains are found among the Antibodies.
  2. On the basis of the presence of heavy chain present, Antibodies can be divided into five types 
  3. They are denoted by Greek letters 
  • α (Alpha), 
  • γ (Gamma), 
  • 𝛿 (Delta), 
  • 𝜀 (Epsilon) 
  • 𝜇 (mu). 
1. lgG :- 
  • The main antibody of the body is IgG and is present in blood and other body fluids. 
  • IgG is the only antibody that can cross the placenta and reach to the embryo.  
  • Among all the antibodies found in the serum IgG has the highest concentration.
  • IgG is produced after the production of IgM.
  • It is a monomeric structure.
2. IgA :-
  • IgA is the only Antibody found in Mothers' milk.  
  • This Antibody is vital for the immunity of the new born baby. 
  • IgA has a dimeric structure
3. IgM :-
  • IgM is the first Antibody which is produced in response to an Antigen. 
  • IgM has a pentameric structure.     
4. IgE :-
  • IgE Antibody primarily works on Basophil and Mast cells and participates in Allergic reactions.
  • It is a monomeric structure.
5. IgD :-
  • IgD antibody is work of defense with WBC.
  • It is a monomeric structure.

Blood and blood group : - 

  1. Blood is a fluidic living tissue which is thick, sticky, red coloured and flow into vessels. 
  2. This is made up of Plasma (nonliving liquid medium) and Blood Corpuscles (living cells). 
  3. Plasma functions to transports the nutrients absorbed by the intestine to various body organs and carry the harmful substances from different organs to the excretory organs.  
  4. Three different types of blood corpuscles are found in the blood.  
  • Red Blood Corpuscles- Transports and exchange gases 
  • White Blood Corpuscles- Protects the body from pathogens Platelets - Protects the blood vessels and helps 
  • to prevent bleeding.  

  1. Blood Groups Firstly, Karl Landsteiner, an Australian Scientist in 1901 classified the blood into different blood groups.  
  2. On the basis of presence or absence of various Antigens on the surface of Red Blood Corpuscles, blood has been classified into various groups.  
  3. Normally these Antigens can be proteins, glycoproteins, carbohydrates or glycolipids.  
  4. These Antigens are synthesized from single allele or related gene which is inherited from both mother and father.  
  5. Two types of Antigens (Antigen 'A' and Antigen 'B') are found on the surface of the Red Blood Corpuscles. 
  6. Based upon the presence of these two Antigens, four blood groups are found - A, B, AB, and O. This classification is called ABO blood grouping. 
  • 'A' type blood has 'A' antigen on the surface of Red Blood Corpuscles.
  • 'B' type blood has 'B' antigen on the surface of Red Blood Corpuscles. 
  • 'AB' type blood has both 'A' and 'B' Antigens on the surface of Red Blood Corpuscles.
  • 'O' type blood is devoid of both 'A' and 'B' Antigens on the surface of Red Blood Corpuscles.
  1. Apart from 'A' and 'B' Antigens, another Antigen named Rh can also be found on the surface of the Red Blood Corpuscles. 
  2. If Rh antigen is present on the surface of the Red Blood Corpuscles, blood is called Rh positive (Rh+). 
  3. The blood in which Red Blood Corpuscles are devoid of Rh Antigen is called Rh negative (Rh-) 
  4. This classification system is called as Rh Grouping. 

  • Persons having 'A' type blood group have IgM type Anti B antibody in their body. 
  • Persons having 'B' type blood group have IgM type Anti A antibody in their body.
  • Persons having 'O' type blood group have IgM type Anti A and Anti B antibody in their body.
  • Persons having 'AB' type blood group have neither Anti A nor Anti B antibody in their body. 
  • If a person with 'A' blood group The persons with is transfused with Type B blood, Anti B antibodies present in his blood will destroy the B type Red Blood Corpuscles. This is the case with every mismatch blood transfusion. Hence, before blood transfusion it should always be taken into consideration that the blood group of the donor and the recipient belongs to the same group. 
  • A person with 'O' type blood group is called Universal Donor while a person with 'AB' blood group is called Universal recipient. 
  • This means that a person with 'O' type blood can donate blood to all and person with 'AB' type of blood can accept blood from all. 

Rh Factor :- 

  1. Rh (Rhesus) factor is a protein of about 417 amino acids.  
  2. It was discovered in a spices of monkey named Macaca rhesus (Macaca mullatta). 
  3. This protein is also found on the surface of the human Red Blood Corpuscles.  
  4. About 85% of the human population the world is Rh+ while the rest 15% is Rh-.  
  5. Five different types of Rh factors - Rh.D, Rh.E, Rh.e, Rh.C and Rh.c are found in humans. 
  6. The frequency of these Rh factors in human population is as follows: 
  7. Among all the Rh factors, Rh.D is most important and predominantly immunologic.  
  • Rh.D (85%)
  • Rh.E (30%)
  • Rh.e (78%) 
  • Rh.C (80%) 
  • Rh.c (80  %).  
  1. Not only the blood group but matching of the Rh factor is important for blood donation. Transfer of blood from Rh + person to a Rh- person results in the development of IgG antibodies against in the recipient. The IgG antibodies so produced works against the Rh factors.  These antibodies destroy the Red Blood Corpuscles possessing the Rh factor by the process of Agglutination.  
  2. Accumulation of large amount of harmful compound called Bilirubin in the blood.  
  3. The excess amount of bilirubin cause impairment of liver and spleen functioning.  This may lead to the failure of the kidney and can ultimately result in the death of the person. 
  4. Here, this is to be noted that the Anti Rh Antibodies are not pre-synthesized rather they are produced after the first contact of Rh negative blood with Rh positive blood.  
  5. If during the pregnancy, mother is Rh negative and the fetus is Rh positive, special attention is required at the time of childbirth.  During the first delivery, blood of the mother and the foetus mixes with each other.  This leads to the production of Rh Antibodies in the mother.  The first baby is born normal.  
  6. The complicity may arise during the second pregnancy, if this time too fetus is Rh negative.  Through placenta, Rh Antibodies present in mother's blood mixes with the circulating foetal blood.  Here they reacts with the Rh proteins present on the surface of the foetal Red blood cells . These Antibodies destroys the Red blood corpuscles through Agglutination and leads hem-agglutination . This may even lead to the death the foetus in the mother's womb . 
  7. Even if the infant survives , he becomes very weak and generally suffers from hepatitis . This disease is called as Erythroblastosis fetalis. 
  9. For the treatment of this disease , mother is vaccinated with anti IgG Antibodies ( anti Rh.D ) within 24 hours of the first delivery . These are called Rhogam Antibodies. 
  10. By destroying the fetal Rh positive blood cells present in the mother's blood , these Antibodies inhibit the production of Anti Rh Antibodies in the mother . Many times , for the treatment of this disease , foetal blood is replaced by the process of transfusion . 
  11. Many times Rh incompatibility is the main cause of hemolysis due to blood transfusion. 

Blood transfusion :-

This is a method in which blood or blood products like platelets , plasma , etc are transferred from the circulatory system of one person to another . 

Dr. Jean - Baptiste Denys , a French physician on 15 June 1667 carried out blood transfusion for the first time. 
He transfused blood in a 15 - year old boy from a sheep . Although ten years later blood transfusion from animals to humans was prohibited .

Requirement for Blood transformation :-

Blood transfusion is absolutely necessary in the flowing situations 
1. At the time of injury or excessive bleeding 
2. Serious blood deficiency 
3. During Surgery 
4. In the condition of deficiency of platelets in the blood 
5. Patients of Hemophilia 
6. Patients of Sickle Cell Anemia 

Process of Blood Transfusion :- 

Blood Transfusion is a scientific process which is accomplished as follows 

(A) Blood Collection 
  1. Before the process of blood collection , donor is examined medically. 
  2. After medical examination , blood from the donor is collected in special sterilised pouches containing anticoagulants. Cannula of suitable capacity is used for blood collection . 
  3. The collected blood is kept in a refrigerator. This prevents the bacterial growth and down regulates the cellular metabolism in the blood. 
  4. The stored blood is subjected to different tests like Blood group , Rh factor , Hepatitis B , Hepatitis C , HIV etc. 
  5. After blood collection , the donor is kept under medical surveillance for some time so that the treatment of any repercussion , if arises due to blood donation could be treated . (Normally no unusual reaction takes place in the body after blood donation ) . 
  6. In humans , plasma is replenished in 2-3 days after the blood donation while after 36 days , blood cells are restored in the blood circulation . 
(B) Transfusion 
  1. Prior to transfusion , the patient's blood is matched with the blood of the donor ( ABO , Rh etc ). Transfusion can only be carried out after this process.
  2. The collected blood is brought out of the storage area just 30 minutes before the start of the transfusion process. 
  3. Blood is transfused only through intravenous mode. This is a four hour long procedure which is mediated by the help of a cannula. 
  4. Medicines are given by the doctor to prevent the transfusion related reactions like fever, chill, pain cyanosis, irregularity of the heart beat and others. 

Type of transfusion :-

On the basis of source of blood , transfusion can be of two types 

1. Allogenic transfusion :- Such a Transfusion which blood collected from other persons is used. 

2. Autogenic transfusion :- Such a Transfusion in which blood collected from the person itself is used .
 
After processing the donated blood can also be segregated into various components like Red Blood Cells Plasma and Platelets. These components are then stored in refrigerated conditions. In addition to humans , blood transfusion can be carried out in animals also. 

Precautions to be taken during Blood Transfusion :- 

1. Matching ABO Antigen in the blood of the patient and the donor. 
2. Testing donor's blood for the absence of any pathogen or harmful substance. 
3. Matching the Rh factor ( especially Rh.D. ) in the blood of the donor and the patient. 
4. Storage of the collected blood in refrigerated conditions ( after completing the desired processes ). 
5. In every circumstance , protecting the collected blood from contamination. 
6. Blood collection and transfusion must essentially be carried out in the presence of a physician . 

The following diseases or infections can occur due to the carelessness observed during the transfusion :- 

1. Infection of HIV - 1 and HIV - 2 ( HIV - Human Immunodeficiency Virus ) 
2. Infection of HTLV 1 and HTLV - 2 ( HTLV - Human T - Lymphotropic Virus ) 
3. Hepatitis -B and Hepatitis C infection . 
4. Creutzfeldt Jacob disease  

Significance of blood group heredity :- 

  1. Many different blood types are found in humans . They are addressed as ABO blood group system . 
  2. The control of expression of the blood group depends on the coordination of three alleles. 
  3. All these alleles are part of the same gene and are represented by I'A' I'B' and I° or i. 
  4. The Antigen A and Antigen B found on the surface of the Red Blood Corpuscles are produced by allele I'A' and I'B' respectively . 
  5. The lº and i alleles are recessive and are not involved in the production of any blood Antigen. 
  6. The expression of blood group in a person is dependent on the interaction between any two alleles. 
  7. Based on the presence of type of alleles , six gene formats of the blood are found in humans. 
  9. O - Blood group is a result of homozygous recessive gene interaction . These genes show Mendelian inheritance . 
  10. There are many applications of Blood Group inheritance . It is mostly used to & solve the paternal disputes , in carrying out successful blood transfusions , in the treatment of neonatal blood hemolysis and hereditary disorders like hemophilia etc. 
  11. The use of blood group inheritance in the solution of paternity related disputes can be understood through the following example : - 
let's assume that two couple are claiming for a child whose blood group is 'B'. The male of one of the couple has 0 ( ii ) blood group and the female has AB ( I'A' I'B' ) blood group . 
The male in second couple has A ( I'A' I'A' ) and female has B ( I'B' i ) blood group . 
In these conditions , as per the Mendel's  law of inheritance , the child can have the flowing possible blood groups.

It is clear from the figure that it is the couple one who could produce a baby of B blood group and they are the actual parents of this child . 
In the similar way knowledge of genetic inheritance is very important for successful blood transfusion and the treatment of the hereditary diseases . 

Organ donation and body donation :- 

  1. Donation of a tissue or an organ to another person by a living or dead person is called Organ Donation . 
  2. The organ donated by the donor is implanted in the recipient's body . In this way the life of the recipient can , not only be saved , but he can enjoy a happy life too . 
  3. Organ donations are generally carried out only after the donor's death . 
  4. About 50 needy people can be helped from an inanimate body . Hence body donation is very important for organ donation . 
  5. A child to ninety years old veteran can donate their organs and body. 

Importance of organ and body donation :- 

  1. The human body is the masterpiece of nature and in no case it can remain permanent. It is said in the Indian philosophy that the human body is made of - air, water, soil, fire and sky. 
  2. Hence, it has become the need of the that even after death humans can be used for the welfare of living beings. This can be possible when after death we could remain alive in others. 
  3. After our death, donation of our eyes, kidneys, liver and other organs could bring happiness in the life of a needy person. This type of donation is categorized as Pure Donation. 
  4. The donation of this category is considered as the best and most holy charity in our Indian philosophy. From the eternal ages, organ donation and body donation were considered as the work of great virtue by our spiritual teachers. 
  5. In ancient times, saint Dadhichi donated his bones for the benefit of the society. There is a need to donate nearly two lakh kidneys every year in India, while availability is only 7000 to 8000 per year. 
  6. Similarly, every year around 50,000 people live in the hope of heart transplantation but availability of heart in India is only 10 to 15. In India, about 50,000 livers are required every year for transplantation, in India, but only 700 people gets this opportunity. More or less the same condition persists with all the other organs. 
  7. According to an estimate, every year about five lakh people in India die due to the organ failure and lack of organs for transplantation. Like organ donation, body donation is such a charity which is absolutely essential for the society. 

Organ donation is essential for two major reasons:- 
  • The organs can be obtained from the dead body and transplanted to the needy. Often, the organ donation is carried out from a brain of dead person. In such cases, the brain of the concerned person ceases function, but other parts of the body remains functional. Organs like heart, liver, kidney and others can be obtained from these dead persons and can be implanted in the needy individuals. However, statistics show that only one person out of a thousand dies in such a way (brain dead). Within six to eight hours of death, the body can be used for eye donation. 
  • To become a best doctor, the medical students need to get training on the dead bodies. Only after the training cum experimental work on dead bodies, medical students can better understand the human body. Thus, organ donation by human beings has become very important these days. It is the ultimate utility of the human body. 

  1. The donors of such a body can become free from their family relations and socio-religious bondages. They act as inscription for the society. It is a matter of great disappointment that due to ancient conservative beliefs, the number of organ donors in India is 0.8 per ten lakhs individuals, whereas in developed countries it is 10 to 30. 
  2. For this purpose, the Government of India, every year, celebrates August 13 as the Organ donation day. 
  3. Many eminent persons of the society have came forward for this noble act. Captain Lakshmi Sehgal (who was involved in the freedom fight with Netaji Subhash Chand Bose) donated cornea at the age of ninety years and filled light in the life of two people. 
  4. Recently, as per his wish, the family members of the famous author Dr. Vishnu Prabhakar donated his body after his death. 
  5. The bodies of the former Chief Minister of West Bengal, Shri Jyoti Basu, the renowned social worker Shri Nana Deshmukh and some other eminent persons were also donated after their death as per their wish. 
  6. Sadhvi Ritambhara and cricketer Gautam Gambhir have also announced to donate their bodies after death. 
  7. Such persons are real saints in true sense and are flag bearers of this revolutionary idea. All of us should realize our duty to donate blood, organs and body after death, so that by this sanctified work our needy brothers and sisters can live a comfortable and graceful life. 

Who can do Organ and Body donation :- 

  1. Any person regardless of religion, race or gender can donate his organ and body. 
  2. Persons less than 18 years of age essentially require the consent of their parents or legal guardians. 
  3. The donor should provide written consent in the presence of two witnesses during his lifetime. 
  4. If it has not been done before death, then the right of organ and body donation lies with the person who has the legitimate authority of the body. 
  5. Organ and body donation in India is legally valid.