Antibodies secreted by plasma cells may have several different effects - (1) They may interact with free (i.e., soluble) antigens causing precipitation; (2) They may interact with surface antigens of the pathogen (i.e., particulate antigens) causing agglutination; or (3) They may promote complement fixation. 1. Precipitation of Soluble Antigens: Antigens may have one or more antigenic determinants. If antigens contain [...]
An immune response is a two-way assault on a pathogen – the cell mediated immune response and the humoral immune response. Cell Mediated Immune Response: Cell mediated immune response is carried out by the T-cells or T lymphocytes (Fig. 11). So, it is also called T-cell immunity. This type of immune response is to defend against pathogens that may invade [...]
TH cells play a central role in the immune response. These cells are specially prolific cytokine producers. Once activated by an antigen, they can use these chemical messengers to induce the formation of TC cells, activate macrophages and formation of many antibodies by B-cells. Functions of TH cell are as follows in the next page (Fig. 10.4): 1. An APC [...]