Immune System and How It Functions: Types and Processes


Humoral and Cellular Immunity

In contrast to the cellular immunity, the humoral one presupposes that the B cells should identify specific pathogens in the blood. The cellular-level response, in its turn, implies that T cells should be involved in the response to any hostile element in the bloodstream. The elements above are identified by locating the MHC markers that are qualified as aberrant (Colco & Sunshine, 2015).

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Cellular Immunity Components

T-cells, therefore, are basically the only components of the cell-mediated immunity. The response itself can be split into three key stages. First, the self cells containing hostile antigens (APCs) bind to T-cells. Afterward, APCs produce interleukins, which cause T-cells activation. Cytotoxic T cells emerge in case the presence of MHC‐I and endogenous antigens is identified and destroy them. If the plasma membrane demonstrates the presence of MHC‐II and exogenous antigens, helper T-cells emerge and release cytokines, particularly, interleukins, so that B cells could release antibodies into the bloodstream (Bennett, Dolin, & Blazer, 2015).

Antigen, Hapten, and Epitopes

Differences Between Antigen and Hapten

In contrast to antigens, which can react with basically any antibodies, haptens can only react to specific ones. In addition, unlike haptens, antigens are immunogenic. Moreover, antigens can activate T cells and B cells whereas haptens do not have the given ability.

Characteristics of Epitopes

It is characteristic of antibodies to bind pathogens so that they could be destroyed and ejected from the body. Epitopes play a crucial role in the process; defined as the antigen determinants, these agents take the form of either carbohydrate or protein. Traditionally, linear (with antibodies bound to the adjacent components of a molecule) and conformational (three-dimensional) epitopes are distinguished as the key ones. Conformational epitopes are usually recognized by antibodies.

Antigens and Antibodies

Among the properties of antigens, the following ones need to be mentioned:

  • Antigens are typically protein and, in some occasions, polysaccharide in nature (Abbas, Lichtman, & Pillai, 2015);
  • Antigens can be found in the red blood cells in soluble state;
  • Antigens typically come in the form of proteins, though they may also be represented by nucleo- and glycoproteins, glycolipids, andpolysaccharides;
  • Antigens may be T-dependent (requiring the help of T-cells) and T-independent (able to stimulate the B-cell directly).

The properties of antibodies include:

  • Emergence as a response to an antibody;
  • Provision of humoral immunity;
  • Causing biological activities;
  • B-cell receptor location.

Typically, five classes of immunoglobulins (IgA, IgD, IgE, IgG, and IgM) are identified. Their functions include:

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  • Activating B-cells (IgE, IgM, IgD);
  • Neutralizing toxins (IgG);
  • Galvanizing the process of phagocytosis (IgG);
  • Protecting against parasites (IgE);
  • Providing localized protection (IgA).

Important Aspects of Humoral Immunity

By definition, humoral immunity is mediated by antibodies. In addition, the fact that the phenomenon can exist in an active and a passive form should be viewed as a unique property of humoral immunity. Humoral immunity implies production of antitoxins that destroy hostile elements in the bloodstream.

Relevant Characteristics of B-Cells

The key function of B-cells concerns the production of antibodies. B-cells form memory cells so that an automated response could be provided and antibodies could be produced automatically in case of recidivism. In addition, B-cells contribute to the production of plasma cells. B-cells are activated as antigens are connected to receptors.

T-Cells and Their Importance in the Immune System

T-cells fall under the category of lymphocytes and are split into two key types, i.e., killer and helper T-cells. The role of T-cells in the human body is reduced to locating the cells that have been mutated or infected with germs and attack them, thus, destroying he mutated and infected cells together with the mutagen or virus contained in them. As T-cells mature, they emerge in lymph nodes and the bloodstream.

Vaccines: Definition and Identification

A vaccine can be defined as the introduction of an agent that resembles the cause of a disease and is typically represented by a weakened microbe to the bloodstream. The development of the antibodies capable of fighting the disease in question triggers the destruction of the mutagen and the mutated cells. B-cells, in their turn, spawn the creation of memory cells that will later on attack the mutagen in case of the disease contraction.

Among the key vaccines that are viewed as imperative in the U.S., the following ones must be mentioned: Hepatitis B1, Rotavirus, Diphtheria, pertussis, Haemophilus influenzae type b4, Pneumococcal conjugate, Inactivated poliovirus, Influenza (IIV; LAIV), Measles, Mumps, Rubella, Varicella, Hepatitis A1, Meningococcal, Tetanus, diphtheria, & acellular pertussis, Human papillomavirus, Meningococcal B1, and Pneumococcal polysaccharide (CDC, 2016, p. 2). Immunization is advised for patients aged 0-6 and is supposed to occur based on a specific schedule.

Recombinant Vaccines, Toxoids, and Antitoxins

Much like antitoxins, toxoids are used as a tool against toxins, whereas recombinant vaccines presuppose the removal of a specific gene from one organism and its following insertion into the other one (i.e., the transfer of antibodies from a healthy organism to the infected one).

Monoclonal Antibodies and Their Clinical Importance

Monoclonal antibodies are the antibody molecules created by a line or clone of cells and incorporating a line of antibody molecules that are completely the same. Monoclonal antibodies allow building immunity against diseases.

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Importance of Hemagglutination Reactions

A hemagglutination reaction implies that red blood cells should be tested for the presence of antibodies against soluble agents in them.

Reference List

Abbas, A. K., Lichtman, A. H. H., & Pillai, S. (2015). Basic immunology: Functions and disorders of the immune system. Philadelphia, PA: Elsevier Health Sciences.

Bennett, J. E., Dolin, R., & Blazer, M. J. (2015). Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. Philadelphia, PA: Elsevier Health Sciences.

CDC. (2016). Recommended immunization schedules for persons aged 0 through 18 years: United States, 2016. Web.

Colco, R., & Sunshine, G. (2015). Immunology: A short course. New York, NY: John Wiley & Sons.

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