WBC 2 Flashcards
Immunity Definition
The process of defense of the body against harmful elements that threaten
our normal health
Classification of immunity
slide number 5-chart
define Innate Immunity (Non-specific Defense)
Non-specific defence systems include the skin and mucous membrane, antimicrobial mechanisms , natural killer cells, phagocytosis, inflammation and fever
types of innate immunity
Mechanical defense- Skin, mucous, hair, cilia, tear, saliva, skin & defaecation
Chemical defense- Acidic pH of Skin, Bactericidal Substance of Sebum, Acidic pH of Stomach, Complement Proteins & Interferon
Defense by NK cells-Lymphocytes either B or T cells
Defense by phagocytic cells-Granulocytes (neutrophils, eosinophil and basophil), monocytes and macrophages kill micro-organisms by phagocytosis
Defense by inflammation & fever-Systemic Response to Inflammation, Inflammatory Cells & Cytokines
Role of Granulocytes & Mononuclear Cells
Granulocytes (neutrophils, eosinophil and basophil), monocytes and macrophages kill micro-organisms by phagocytosis
Role of Neutrophil in Phagocytosis
- Margination: Neutrophil movement towards the wall of capillary in the area of infection
- Diapedesis: Squeezing through pores in capillary wall and entering the tissue
- Chemotaxis: Attraction to the site of inflammation by chemicals released at the site of infection by various cells
- Opsonization: Complement factors + antibodies gets attached to bacteria.
- Endocytosis
- Degranulation
- Exocytosis
Roles of B Lymphocytes in Immunity
concerned with humoral immunity:
➢ B cells binds to an antigen → differentiate into plasma cells → secrete
antibodies (immunoglobulins) → attack & neutralize antigens.
➢ Major defence against bacterial infections
Roles of T Lymphocytes in Immunity
T lymphocytes are concerned with cellular immunity:
➢ T cells activated by antigen presenting cells → activated T cells
release cytotoxic substances → destroy the cells with the antigen
➢ Major defence against viral or fungal infections & tumors.
ADAPTIVE Immunity:
humoral immunity
cellular immunity
T4 cells induce development of both cellular and humoral immunity.
- look at slide no 11
Humoral Immunity:
due to the presence of antibodies in the body:
* Antibodies are formed by plasma
cells. Plasma cells are developed from activated B cells in response to antigen.
* This immunity works mainly against extracellular organisms such as bacteria and the antigens dissolved in the body fluids.
Cellular/cellular mediated Immunity
due to the presence of cytotoxic T cells in the body:
* These cells develop and proliferate in
response to a particular antigen and kill
that organism
* This immunity is particularly effective
against intracellular organisms like
viruses, parasites and fungi, cancer cells, tumor cells, and transplanted tissues.
B lymphocytes
produce circulating antibodies in the globulin fraction of the plasma proteins (immunoglobulin)
Steps in Humoral Immunity
- Presentation of antigen
- Activation of B cells
- Differentiation of B cells into plasma cells
- Proliferation of plasma cells and antibody production
- Killing of the invaders by antibodies that include activation of
complement system - Formation of memory B cells and subsequent immunological
responses
mechanism of humoral immunity
pg 14 slide
Components of Cellular Immunity
- Helper T Cells (T4 Cells)
❖ The helper T cells are called T4 cells as they contain CD4 protein on their cell surface. - Cytotoxic T Cells
❖ These are called T8 cells as they contain CD8 protein on their cell membrane. - Memory T Cells
❖ A small subset of T cells remains in the tissue as memory T cells.
