antigens and antibodies

Both types of acquired immunity are initiated by ___

ANTIGENS

interact specifically with an antigen receptor. Although antigenic, some may not necessarily induce a specific immune response (Bacteria, viruses, parasites, foreign tissues, and large proteins)

Antigens:

an immunologically active site on an antigen that binds to a T-cell receptor or to an antibody

Epitopes:

produced by B cells; resembles a Y-shaped molecule with two antigen-binding sites

Antibodies:

directly attack antigens, destroying or neutralizing them through the processes of agglutination, precipitating the toxins out of solution, neutralizing antigenic substances, and lysing the organism’s cell wall

Immunoglobulins:

• Also known as T-cell immunity

• destruction of microbes that are able to survive in the cytoplasm or phagocytic vesicles of infected cells

• can sometimes be harmful to the host, as they are responsible for the rejection of transplanted tissue and certain autoimmune diseases

• T cells are developed in bone marrow and mature in the thymus → Mature T cells exit and migrate to lymphoid organs via circulation

Cell-mediated Immunity

• Also known as T-cell immunity

Cell-mediated Immunity

• destruction of microbes that are able to survive in the cytoplasm or phagocytic vesicles of infected cells

Cell-mediated Immunity

• can sometimes be harmful to the host, as they are responsible for the rejection of transplanted tissue and certain autoimmune diseases

Cell-mediated Immunity

• T cells are developed in ____ and mature in the ____ → Mature T cells exit and migrate to lymphoid organs via ____

bone marrow; thymus; circulation

These lymphocytes are critical players in immune responses against intracellular threats such as viruses, abnormal/cancer cells, and intracellular bacteria)

• recognize and destroy infected cells or “nonself” cells

• kill their target cells by inducing programmed cell death (apoptosis)

Cytotoxic T cells (CD8+)–

These lymphocytes are critical players in immune responses against intracellular threats such as viruses, abnormal/cancer cells, and intracellular bacteria)

Cytotoxic T cells (CD8+)–

• recognize and destroy infected cells or “nonself” cells

Cytotoxic T cells (CD8+)–

• kill their target cells by inducing programmed cell death (apoptosis)

Cytotoxic T cells (CD8+)–

most numerous; major regulator of virtually all immune functions; forms lymphokines

produce different cytokines that modulate the immune system; help mount effective responses against foreign invaders.

Helper T cells (CD4+)–

preventing the cytotoxic cells from causing excessive immune reactions that might be damaging to the body’s own tissues. Also regulator T cells. plays an important role in limiting the ability of the immune system to attack a person’s own body tissues (immune tolerance)

Suppressor T cells –

Also B-cell immunity or antibody-mediated immunity mediated by antibodies present in different body fluids or secretions, such as saliva, blood, or vaginal secretions.

Bone marrow → secondary lymphoid organs → plasma cells (produce antibodies) and memory cells

Memory B cells are long-lived and remain in the circulation until they reencounter a particular antigen.

When this takes place, memory B cells generate a secondary antibody response by differentiating into plasma cells.

Humoral Immunity