Humoral + Cell Mediated response

Where are B lymphocytes produced + mature?

• produced - stem cells in bone marrow

• mature - spleen + lymph nodes

Where are T lymphocytes produced + activated?

• produced - stem cells in bone marrow

• activated - thymus gland

How do B and T cells detect pathogens?

have antigen receptors complementary to specific antigens

Describe structure of antibodies

• Y shaped proteins with 4 polypeptide chains + 2 binding sites

• disulphide bridges holding polypeptides tgt

• hinge region allows flexibility for binding site to be placed at diff angles

How do antibodies bind to pathogens?

• bind to specific antigen on pathogen → antigen-antibody complex

• renders antigen inactive by agglutination

• increases rate of engulfment by phagocytes

What happens in humoral response when pathogen enters body?

• when in contact with B-cells with complementary antigen receptors engulf the antigen + digest it → display fragments of antigen on its cell surface membrane

• non-specific macrophages also engulf + digest pathogen → display antigen on cell surface membrane

What happens when macrophage comes in contact with T cell in humoral response?

• comes in contact wit T cell with complementary antigen receptor to pathogen antigen on surface

• both bond and T cell activated → T helper cell

• T helper cell binds with B cell stimulating it to undergo clonal expansion → differentiate into plasma cells + memory cells

• plasma cells secrete antibodies specific to pathogen’s antigen to destroy it

• memory cells stay to bring about secondary response

Explain what happens in cell-mediated response

• T cell binds to cell with non-self antigens it gets activated + divides rapidly to from 3 types:

  • T killer cells - destroy cells by causing lysis

  • T helper cells - detect antigens to secrete cytokines to stimulate B cell

  • T memory cells - remain to bring about secondary response