What type of barrier is the mucus membrane?

Which antibody is present in high concentration in the initial milk (colostrum)?

What is true about $T-lymphocytes$ in mammals?

Which of the following cells are associated with the immune system of the body?

Fill in the blanks: Our body, when it encounters a pathogen for the first time, produces a response called . . . . . . $a$ . . . . . . response, which is of . . . . . . $b$ . . . . . . intensity. Subsequent encounters with the same pathogen elicit a . . . . . . $c$ . . . . . . intensified . . . . . . $d$ . . . . . . response.

Which pair of white blood cells is involved in cellular barriers?