Immunology

• Adaptive immunity is mediated by lymphocytes, including B cells and T cells.
• Immunological memory is the ability to recognize previously encountered antigens.
• The mechanism of immunological memory involves the activation of the third line of defence, also known as the adaptive immunity.
• Immunological memory involves the activation of T cells and B cells.
• Memory cells acquired through immunological memory result in faster response to the same invader next time.
• There are four basic types of immunity: active immunity, passive immunity, natural immunity, and artificial immunity.
• Active immunity is acquired through exposure to antigens, resulting in the production of memory cells.
• Artificially acquired immunity, also known as vaccinations, involve the introduction of antigens that have been pretreated to be immunogenic but not pathogenic into the body.
• Passive immunity can be naturally acquired from the transfer of IgG antibodies from mother or from mother to baby in milk during breast feeding, or artificially acquired through intravenous injection of immunoglobulins.
• The immunization schedule in Malaysia includes vaccinations against infectious diseases such as measles, mumps, rubella, polio, and tetanus.
• Edward Jenner discovered vaccination in 1796 when he observed that milkmaids who had been infected with cowpox were protected from the more serious disease called smallpox.
• Edward Jenner inoculated healthy people with cowpox and found that they were protected from smallpox, a form of immunisation called vaccination because the Latin word for cowpox is vaccinia (vacca =cow).
• The cowpox antigen stimulates the production of antibodies that are effective against both viruses.
• Whole microbe vaccines use whole organisms, examples include Salk polio vaccine and Typhoid.
• Killed vaccines use heat, formalin, etc to kill the microbe, examples include Salk polio vaccine and Typhoid.
• Live vaccines use attenuated strains, organisms cultured to reduce its pathogenicity but still retains some of the antigens of the virulent form, examples include Sabin polio vaccine and BCG.
• Subunit vaccines use subunits instead of whole organisms, examples include toxoid and polysaccharides.
• Toxoid is a toxin converted to a toxoid to reduce the pharmacological activity of the toxin, examples include tetanus toxin and diphtheria toxin.
• Polysaccharides use polysaccharide as antigen, usually linked to protein to get better stimulation of Ab production, examples include Strep Pneumoniae.
• DNA, RNA, mRNA vaccines use DNA, RNA, mRNA, examples include COVID-19 vaccine.
• Major Histocompatibility complex (MHC) or Human leucocyte Antigen (HLA) are self antigens found on the membranes of all nucleated cells in the body of vertebrates.
• The tissue/organ from another individual is considered as a foreign antigen by the recipient.
• The reason why tissues/organs from one individual destroyed when introduced into another person is due to the tissues of the donor and the recipient being incompatible.
• The cluster of genes named as MHC encodes proteins that determine if a tissue/organ transplanted between two individuals will be accepted or rejected.
• Organ transplant refers to the act of transferring cells, tissues, or organs from one site to another.
• The organ transplantation from a donor will be viewed as a foreign invasion by the recipient immune system.
• Organ transplant is still performed if it is the only possible treatment for a disease.
• The immune system will attack and reject any transplanted organ that it does not recognize as self, making organ transplant a serious barrier to potentially life-saving treatment.
• Organ transplant can be suppressed by drugs, but this type of treatment suppresses all immune function, making the host susceptible to infectious diseases.
• The first human kidney transplant, attempted in 1933 by a Russian surgeon, Voronoy (1895 – 1961), failed because there was a mismatch of blood types between donor and recipient.
• The incompatibility caused an almost immediate rejection of the kidney, and the patient died 2 days after.
• The sensitization phase in graft rejection involves the immune system's sensitization to the donor antigen through the recipient's CD8+ Tc and TCR.
• Prednisone is an immunosuppressive steroid (corticosteroids) that inhibits inflammatory cells and suppresses the expression of inflammatory mediators to prevent and treat rejection.
• Immunosuppressive drugs can aid in the survival of transplants by suppressing the immunologic attack on grafts.
• Azathioprine is a type of mitotic inhibitor that inhibits T-cell proliferation to prevent and treat rejection.
• Muromonab-CD3 are monoclonal antibodies that target CD3 on T-cells, preventing activation of T-cells.
• The effector stage in graft rejection involves the immune system's destruction of the graft through mechanisms such as cell-mediated reactions, antibody-dependent cell-mediated cytotoxicity (ADCC), and antibody-dependent complement-mediated cytotoxicity (ADCC).
• Cyclosporin is an immunosuppressive drug that inhibits the transcription of IL-2, reducing the function of effector T-cells.
• Daclizumab are monoclonal antibodies that target IL-2 receptor on activated T cells, inhibiting IL-2-mediated activation of lymphocytes.
• The response to major histocompatibility antigens involves recognition of both the donor MHC molecule and an associated peptide on MHC molecule.