Question

Differentiate primary adaptive immunity from secondary adaptive immunity. Differentiate active secondary immunity from passive secondary immunity.

Answer 1

Primary adaptive immunity B-cells and T-cells are the responding cells. Primary contact with an antigen results in causing primary immune response. In 7-10 days level of antibodies reach at peak. Longer lag phase. IgM is mainly the first antibody produced. IgG is also produced in traces . To establish immunity it takes longer time. Rapid declination of antibody level. Primary immune response is given by Thymus dependent and Thymus independent antigen. Antibody affinity is lower for its antigen. Appears mainly in lymph nodes and spleen.

Secondary adaptive immunity Memorycell is the responding cell. Second and subsequent exposure of the same antigen causes secondary adaptive immunity. In 3-5 days level of antibodies reach at peak. Shorter lag phase. IgG antibody is produced mainly. IgM is also produced in traces. To establish immunity it takes shorter time. Level of antibody remains high for longer time. Secondary immune response is given by Thymus dependent antigen. Antibody affinity is greater for its antigen. Appears mainly in bone marrow followed by lymph nodes and spleen.

Active Secondary immunity When a host is exposed to antigens, which are in the form of living or dead microbes or in the form of protein, antibodies are produced in the body of the host. This is called active secondary immunity. Cell mediated and humoral immunity are involved. Antibody production is involved. Exposure to a pathogen or antigen of pathogen is required. Active functioning of the individuals immune system occurs. Long lived protection. It is very effective for a prophylaxis disease. T-cells, B-cells and antigen presenting cells are involved. Arises naturally when exposed to clinical infections. Long lasting memory immune cells are formed.

​​​​​​Passive secondary immunity When ready made antibodies are directly induced to the body of the host to fight against foreign agent, it is called passive secondary immunity. Ready made antibodies can only confer immunity. No antibody production is involved. (Directly transferred.) Exposure to a pathogen or an antigen of pathogen is not required. Active functioning of the individuals immune system doesn't occurs but passive functioning occurs. Transient protection. Effective as a post exposure remedy. Immune cells are not involved. Naturally arises when foetus recives antibodies from mother through placenta or by breast feeding, the infant ingest antibodies from the mother's milk.(colostrum) Formation of memory immune cells doesn't occurs.