All of the following statements about carbohydrateantigen are true except aEUR'
Memory response is seen Antigen Antigen is a substance that stimulates the production of antibody, when introduced into the body. Type of antigen A. Based on chemical nature - Based on chemical nature, antigens can be : - i) Proteins ii) Polysaccharide (Carbohydrates) iii) Lipids iv) Nucleic acids - Proteins are most immunogenic, while lipids & nucleic acids are least immunogenic. - Polysaccharides (carbohydrates) are less immunogenic than protein antigens, but are more antigenic than lipids & nucleic acids. B. Based on immune response - On the basis of immune response, antigens can be divided into : - i) T-cell dependent antigens ii) T-cell in dependent antigens i) T-cell dependent antigens Most of the protein antigens are T-cell dependent. Their immune response is dependent on T-cell activation. After exposure, these antigens are presented to T-cells (helper T-cells) by antigen presenting cells. These primed T-cells then secret cytokines that induce B-cells to produce antibody against that paicular antigen. T-cell dependent reaction has memory response, i.e., subsequent exposure to same antigen result in :? a) A more rapid production of antibodies b) Produced in greater amounts c) Produced for a longer period of time. T-cell independent antigens carbohydrate (Polysaccharide) antigens are T- cell independent. Their immune response does not require activation of T-cells. These antigens directly stimulate B-cells without processing by antigen presenting cells. There is no memory response Protein antigen Carbohydrate antigen * More immunogenic * Less immunogenic * T-cell dependent * T-cell independent * No tolerence * Immunological tolerance occurs * Induce Production of all type of antibodies * Induce production of IgM and IgG only * Memory response is seen * No memory response * Require processing by antigen presenting cells. * Do not require processing * Quickly metabolized * Slowly metabolized
It has lower immunogenicity
Memory response is seen
Cause polyclonal B cell stimulation
Does not require stimulation by T cells