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.
Antibodies protect against substances prior to cell infection. Antibodies are produced by a type of white blood cell called a B cell (B lymphocyte). B cells develop from stem cells in bone marrow.When B cells become activated due to the presence of a particular antigen, they develop into cells called plasma cells.he antigen-binding site is the area of the antibody that recognizes the specific antigenic determinant and binds to the antigen. Since different antibodies recognize different antigens, antigen-binding sites are different for different antibodies.