Human Immunology Course 2022

Running head: Human Immunology 1
Human Immunology
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Human Immunology 2
Types of vaccination
Introduction
Vaccination is the inoculation of antigen or vaccine into the body whereas immunization is the
actual process of inducing an immune response which can be cell-mediated or humoral in the
recipient. The elements of the immune system can be broken down into two major categories
namely, the innate resistance system which includes the skin, mucosal barriers and phagocytes,
and the adaptive system which is comprised of humoral and cellular immunity. Both of these
systems exist in constant interaction to ensure that there is an effective immune response.
Immunizations stimulate body immunity through specific mechanisms after the body has first
spotted the threat to be either immunization or a pathogenic agent. The innate immune system
plays an important role in the early detection; however, B-cells undertake this function. The
process of detection starts once the immune system detects epitopes on antigens after which
multiple processes of the innate immune system will provide an appropriate feedback to the
issue. Then the mechanisms of the innate immunity become attached to the agent and help in its
elimination by antigen-presenting cells which develops the antigens from the current microbe
and add in the resultant antigen alongside the MHC protein onto the cell’s surface of the resultant
antigen.
In the case of a viral antigen, it will be engulfed with MHC I protein and processed by the
resulting cell to a CD8 cell which will possibly activate cell-mediated immunity. For parasitic
antigen or bacterial, the MHC II protein will engulf the antigen and processed by the antigen-
presenting cell to a CD4 cell which will probably activate antibody-mediated immunity. There
are three major types of vaccines namely Live Attenuated Vaccines (LAVs), killed or inactivated
vaccine, and a subunit vaccine. The LAVs are derived from already weakened disease-causing

Human Immunology 3
pathogens such as vaccines against mumps, chickenpox and measles. Killed vaccines are
produced from already killed disease-causing microbe using physical or chemical processes.
They are more stable than LAVs. Example include vaccines against hepatitis A, influenza among
others. Subunit vaccines are like the killed vaccines but the only difference is that they only
contain the antigenic components of the pathogen. An example is the Hepatitis B vaccine (Clem,
2011).
With the current increase in the rate of infection and multiple forms of diseases, there is a need to
explore further on human immunology with a particular emphasis on vaccination. This essay will
examine in details the major types of vaccination.
Mechanisms by which Immunization stimulate Immunity
Antigens are elements of proteins found in disease-causing micro-organisms and the vaccines
made to fight them. The antigens trigger multiple cells in the immune system in addition to
macrophages, B and T cells. The ingestion of antigens by macrophages marks the beginning of
an immune response. The Major Histocompatibility Complex (MHC) transports some of the
antigen fragments, after being broken down by macrophages, to the cell’s surface, where they are
exposed but still bound to the MHC molecule. The exposed antigen fragments are identified by T
cells, which trigger B cells to release antibodies to the fragments and further stimulate other
immune mechanisms. In the case of a viral antigen, it will be bound with MHC I protein and
processed by the resulting antigen cell to a CD8 cell which will possibly activate cell-mediated
immunity. For parasitic antigen or bacterial, the MHC II protein will engulf the antigen and
processed by the final antigen cell to a CD4 cell which will probably trigger antibody-mediated
immunity (Pulendran & Ahmed, 2011).