The principle function of the lymph node in the man is
Destruction of old $ RBC$
Destruction of old $WBC$
Collection and destruction of pathogens blood
Production of $WBC$
What plays an important role in primary and secondary response?
A condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue is called
Active immunity is obtained by
Some people who have suffered from a disease may not be affected again during their life time; such immunity is called