The primary and secondary response are carried out with the help of two special types of lymphocytes present in our body that is $B$-lymphocytes and $T$-lymphocytes.

$B$-lymphocytes produce an army of proteins in response to pathogens into our blood to fight with them. These proteins are called antibodies.

$T$-lymphocytes themselves do not secrete antibodies but help $B$-lymphocytes to produce antibodies.