Chapter 17, Problem 1R

Contrast the terms in the following pairs:

1. a. innate and adaptive immunity
2. b. humoral and cellular immunity
3. c. active and passive immunity
4. d. T_H1 and T_H2 cells
5. e. natural and artificial immunity
6. f. T-dependent and T-independent antigens
7. g. CD8⁺ T cell and CTL
8. h. immunoglobulin and TCR

Summary Introduction

To review:

The comparison and contrast of the given terms.

Introduction:

The immune system is defined as the group of cells or tissues or organs that functions against the foreign substance to provide immunity. The immunity is classified into two categories, innate and adaptive.

Immunoglobulins are produced by plasma cells, which contains the antigen binding site that allows the antigen to bind. It is found in blood, tissues and other body fluids to make the immune system.

Antibodies and lymphocytes are the major elements in the adaptive immune system. The lymphocytes consist of B cells, cytotoxic T cells and Helper T cells which are involved in the adaptive immune response against the infectious pathogens.

Explanation of Solution

1. a. Innate and adaptive immunity: Innate immunity is a non-specific defense mechanism, which acts immediately after the exposure of antigens or foreign substances on the body. Adaptive immunity is an antigen-specific immunity that adapts the immune system by the formation of immune cells or memory cells for a specific antigen. Adaptive immunity acquires either actively or passively when a person is exposed to microorganism or foreign substances. The active and passive acquired immunity can be obtained by natural or artificial ways.
2. b. Humoral and cellular immunity: Humoral immunity is mediated by antibodies that are secreted by plasma cells to confer the immune response against the freely circulating antigens on the surface of the B cells. The cell-mediated immune response is mediated by T lymphocytes to eliminate intracellular pathogens by phagocytosis, Natural killer cells (NK), the formation of cytotoxic T lymphocytes and releases cytokines. It involves phagocytosis and cell apoptosis with the help of cytotoxic T lymphocytes (CTL).
3. c. Active and passive immunity: The immune system which acquires immunity at the time of exposing to the foreign substances is termed as the active immunity. Whereas, the transfer of antibodies from one to another for acquiring the immunity either by natural or artificial ways is termed as passive immunity.
4. d. T_H1 and T_H2 cells: T helper 1 cells plays a major role in the activation of macrophages, T cells and natural killer cells in the cell-mediated immune response. Whereas, the T helper 2 cells helps in the production of eosinophil, IgE and IgM cells.
5. e. Natural and artificial immunity: The immunity develops by birth, when the exposure of the live microorganisms, which leads to the development of memory cells for particular diseases, is known as natural immunity. While a small quantity of vaccines is given to expose the immunity against particular diseases is known as artificial immunity.
6. f. T-dependent and T-independent antigens: T-dependent antigen requires the T helper cells for the antibodies produced against the antigens. While in T- independent antigen, B cell produces the antibodies directly without the requirement of T cells.
7. g. CD8+ cell and CTL: CD8+ cells are also known as cytotoxic T cells which involve in adaptive immune systems, contains the surface proteins which is responsible to kill the intracellular infections caused by bacteria, virus and some cancer cells. The cytotoxic T lymphocyte cells generate the cytotoxic T cell, which targets the cell by pore-forming protein perforin and thereby it penetrates the protease enzyme to induce the apoptosis.
8. h. Immunoglobulin and TCR: Immunoglobulins are produced by plasma cells, which contains the antigen binding site that allows the antigen to bind. It is found in blood, tissues and other body fluids to make the immune system. Antibodies are Y shaped molecules which contain two light chains and two heavy chains that are interlinked by disulfide bridges. The immunoglobulins are classified into five classes such as IgG, IgA, IgM, IgD, and IgE, based on their role in the immune system against the antigenic exposure. Whereas the T cell receptors are present on the surface of the T cells which helps antigen to recognize and allow binding on the surface of the major histocompatibility molecules.