12th Zoology

Genetic basis of organ transplants

Genetic basis of organ transplants :

Success of organ transplants (ie., Cornea, Kidney, Heart, Liver, Bone
marrow) and skin grafts depends on a proper matching of histocompatibility
antigens that occur in all cells of the body. Chromosome 6 of mouse contains
a cluster of genes known as the major histocompatibility complex (MHC),
which in humans is called human leukocyte antigen (HLA) complex. The
alleles of HLA genes determine the histocompatibility ie., the compatability
between donor and recipient tissues in transplants. (Genetic basis of organ transplants)

Process of graft rejection : (Allograft)

When the graft or tissue involves two genetically distinct members of
the same species, graft rejection occurs because the antigens of the graft and
host being different, the immune response of the host rejects the graft. The
graft dies, decays and is eliminated from the host. The host also reacts to the
graft and shows the following symptoms. 1.Skin rashes, 2. Fluid accumulation
in spleen and enlargement (Splenomegaly), 3. Emaciation (becoming
thin), 4. Diarrhoea, 5. hepatomegaly, 6. Anaemia and general immune suppression, 7. Damage in bile ducts, 8. Increased bilirubin synthesis etc. (Genetic basis of organ transplants)

Both cell mediated and humoral immune responses follow in rejection.
Sensitized T cells (lymphocytes), macrophages, plasma cells are all involved
in the primary or first set rejection. In the secondary or second set reaction,
B cells (B lymphocytes) and their antibodies are involved. In the cell
mediated reaction substances such as interleukin 1 (IL-1), Interleukin – 2
(IL-2) etc take part. The final lysis of the graft is achieved by lymphotoxins
or TNF (Tumour necrosis factors) or proteolytic enzymes.

In clinical fields, graft rejection is prevented by : 1.Blood groups
estimation (ABO and Rh) in the host, 2. Testing the presence of cytotoxic
antibodies in the host serum, 3. Cross matching of tissues (Host Vs graft)
prior to transplantation, 4. Giving immunosuppressive drugs like cyclosporin
and steroids etc to the host, 5. Total lymphoid tissue irradiation etc.
In recent years, the cloning technology promises to bring solution to
the problems of graft or tissue rejection in transplantation surgery. By stem
cell technology and cloning of cells, organ culture is feasible. Organs
cultured from the same embryo or individual are safe and valuable for
transplantation surgery. (Genetic basis of organ transplants)

Related Topics in Zoology:

Bio Zoology All Important Topics

  1. Microbiology Introduction and History of Medical Microbiology

  2. Pasteur, Koch, Lister

  3. Structure of Viruses

  4. Viral genetics

  5. Virus Culture

  6. Viral Diseases

  7. Bacteria Structure Culture

  8. Bacterial Genetics

  9. Bacterial Diseases

  10. Protozoan microbiology

  11. Pathogenecity of Microorganisms

  12. Antimicrobial Resistance

  13. Antibiotics and Chemotherapy

  14. AIDS – HIV

Unit 3 – Immunology Topic List Zoology


  2. Acquired Immunity

  3. Structure and Functions of the Immune System

  4. Peripheral Lymphoid Organs

  5. Secondary Lymphoid Organs

  6. Antigenic determinants and epitopes

  7. Antibodies – Immunoglobulins

  8. Transplantation immunology

  9. Genetic basis of organ transplants

  10. Immune system disorders

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