Which cells secrete interferons?

The development of a quick immune response in a person infected with deadly microbes by administering preformed antibodies is known as:

Breastfeeding can be categorized under which type of immunity?

How many heavy polypeptide chains are present in each antibody molecule?

What percentage of lymphoid tissue in the human body is constituted by $MALT$ (in $\%$)?

$T$-Lymphocytes originate from