McKenna's Pharmacology for Nursing, 2e

C H A P T E R 1 5  Introduction to the immune response and inflammation 237

Virus

Interferon release

Cell

Protein release

Cell invasion

Cell injury

Histamine release

B cell

Hageman factor

Rubor Calour Tumour Dolour

Effector T cells

Helper T cells Suppressor T cells

Memory cells

Plasma cells

Kinin activation

Antibody formation

Interleukins

Leucocyte activation Pyretic effect

Antigen–antibody complex

Cell death Inflammatory response

Complement activation

Inflammatory reaction

Immune reaction

Inflammatory reaction

FIGURE 15.6  Interrelationship of immune and inflammatory reactions.

PATHOPHYSIOLOGY INVOLVING THE IMMUNE SYSTEM Several conditions can arise that cause problems involv­ ing the immune system. These conditions, many of which are treated by drugs that stimulate or suppress the immune system, include neoplasm, viral invasion, auto­ immune disease and transplant rejection. Neoplasms Neoplasms occur when mutant cells escape the normal surveillance of the immune system and begin to grow and multiply. This can happen in many ways. For example, ageing causes a decreased efficiency of the immune system, allowing some cells to escape detec­ tion. Location of the mutant cells can make it difficult for lymphocytes to get to an area to respond. Mutant cells in breast tissue, for example, are not well perfused with blood and may escape detection until they are quite abundant. Sometimes cells are able to avoid detection by the T cells until the growing mass of cells is so large that the immune system cannot deal with it. Tumours can also produce blocking antibodies that cover the antigen-receptor sites on the tumour and prevent rec­ ognition by cytotoxic T cells. In addition, a weakly antigenic tumour may develop; such a tumour elicits a

KEY POINTS

■■ The response to the inflammatory stimuli involves local vasodilation, increased capillary permeability and the stimulation of pain fibres. These reactions alert the person to the injury and bring an increased blood flow to the area. ■■ The immune response provides a specific reaction to foreign cells or proteins. ■■ T cells can be cytotoxic, destroying non–self- cells; helper, augmenting an immune reaction; or suppressor, dampening the immune response to save energy and prevent cell damage. ■■ B cells produce antibodies in response to exposure to specific antigens or proteins. Antibodies react with this antigen to produce an antigen–antibody complex that activates complement and will result in destruction of the antigen. ■■ Other mediators that affect the immune and inflammatory responses include interferons, tissue necrosis factor and interleukins. ■■ The immune and inflammatory responses work together to protect the body from injury or foreign pathogens.