IMMUNOLOGY

Detailed explanation-1: -B cells activate humoral immunity, whereas T cells activate cell-mediated immunity. The major difference between humoral and cell-mediated immunity is that humoral immunity produces antigen-specific antibodies, whereas cell-mediated immunity does not.

Detailed explanation-2: -Figure 8.1. The role of effector T cells in cell-mediated and humoral immune responses to representative pathogens.

Detailed explanation-3: -T helper cells aid in both the humoral and cellular immune response. CD4* T cells are helper cells that bind to the major histocompatibility complex (MHC) II class molecules on B cells and antigen-pressing cells (APCs).

Detailed explanation-4: -The humoral immune response is mediated by antibody molecules that are secreted by plasma cells.

Detailed explanation-5: -There are two main mechanisms of immunity within the adaptive immune system – humoral and cellular. Humoral immunity is also called antibody-mediated immunity. With assistance from helper T cells, B cells will differentiate into plasma B cells that can produce antibodies against a specific antigen.

Detailed explanation-6: -Th1 helper cells lead to an increased cell-mediated response (primarily by macrophages and cytotoxic T cells), typically against intracellular bacteria and protozoa. They are triggered by the polarising cytokine IL-12 and their effector cytokines are IFN- and IL-2.