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.ntibodies recognize specific antigens by identifying certain areas on the surface of the antigen known as antigenic determinants. Once the specific antigenic determinant is recognized, the antibody will bind to the determinant.
The Underground Railroad. For the 240 years from the first African slave until 1860, slaves ran and some escaped to freedom. In 1850, the value of a trained slave was around $2500 - an enormous sum at a time more than ten times the average person's annual earnings.
With all the danger, there was little chance of success. But if he did make it ... freedom. The word was too much for many slaves even to contemplate, much less attempt. But according to at least one estimate, during the 1800s, more than 100,000 slaves would take their chances to start a new life. The Underground Railroad was their ticket to freedom [source: Freedom Center].