What is the immune response called when our body encounters a pathogen for the first time?

In an autoimmune disease,.........

Select the incorrect statement with respect to acquired immunity.

State the number of polypeptide chains in $H_{2}L_{2}$ (an antibody molecule).

In the human body,cell-mediated immunity is mediated by which of the following?

The spleen is a large bean-shaped organ which primarily acts as a filter of the blood by trapping blood-borne microorganisms. Which of the following statements is correct regarding the spleen?