Also, there are differences in the immune response depending on how many times you have been infected by the same pathogen. When the antigen infects the body for the first time, this is the primary immune response. It is slow and weak due to few B-Cells being able to produce the complementary antibody. As this immune response takes longer, the infected organism will typically show symptoms. The T-cells and B-cells produce memory cells, which remember the antigen to produce the complementary antibody if it infects the body again.