Early Indus Valley Civilization ... their Geograhpy, their customs and Indo-Aryan civilization with the earliest caste system.
Antibodies contribute to immunity in three main ways: they can prevent pathogens from entering or damaging cells by binding to them; they can stimulate removal of a pathogen by macrophages and other cells by coating the pathogen; and they can trigger direct pathogen destruction by stimulating other immune responses such as the complement pathway.
Activated B cells differentiate into either antibody-producing cells called plasma cells that secrete soluble antibody or memory cells that survive in the body for years afterward in order to allow the immune system to remember an antigen and respond faster upon future exposures.sing this binding mechanism, an antibody can tag a microbe or an infected cell for attack by other parts of the immune system, or can neutralize its target directly (for example, by blocking a part of a microbe that is essential for its invasion and survival).