Secondary immune response

Secondary immune response The secondary immune response occurs when a person is exposed to the same antigen again. During this time, immunological memory has been established and the immune system can start producing antibodies immediately . Sl.No Active Immunity Passive Immunity Active immunity is produced actively by host’s immune system. Passive immunity is received passively and there is no active host participation. It is produced due to contact with pathogen or by its antigen. It is produced due to antibodies obtained from outside. It is durable and effective in protection. It is transient and less effective. Immunological memory is present. No memory. Booster effect on subsequent dose is possible. Subsequent dose is less effective. Immunity is effective only after a short period. Immunity develops immediately. Table . Differences between active and passive immunity Sl.No Primary Immune Response Secondary Immune Response It occurs as a result of primary contact with an antigen. It occurs as a result of second and subsequent contacts with the same antigen. Antibody level reaches peak in to days. Antibody level reaches peak in to days. Prolonged period is required to establish immunity. It establishes immunity in a short time. There is rapid decline in antibody level. Antibody level remains high for longer period. It appears mainly in the lymph nodes and spleen. It appears mainly in the bone marrow, followed by the spleen and lymph nodes. Table . Differences between primary and secondary immune responses XII Std Zoology Chapter XII Std Zoology Chapter Immunology