Role of Vaccination

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Vaccination gives artificially acquired immunity from a disease. Once common diseases, such as small pox, diphtheria and polio, are now uncommon because of successful vaccination programs. Smallpox was the first disease for which a vaccine was developed. Edward Jenner did this in 1796. The vaccination program that was started in the 1960s was so successful that the World Health Organisation (WHO) has declared it eradicated. Diphtheria vaccine is given as part of a triple antigen injection that protects against diphtheria, tetanus and whooping cough. In 1990, WHO stated that 80% of children had been vaccinated against this disease. There continues to be outbreaks of this disease and continued vaccination is recommended. It is no longer thought of as a major child killer. Polio caused thousands of children to become paralysed every year. A vaccine was introduced in 1955. It became available as an oral vaccine in the 1960s. Worldwide, the number of cases is down by 80%. B and T lymphocytes interact as they are both attacking the same antigen. Helper T cells (see below) stimulate B cells and T cells to clone. The mechanisms that allow interaction between B and T lymphocytes The T lymphocytes that help B lymphocytes are called helper T cells (Th cells). If a B cell has an antigen on its surface, there is a risk that a T cell will recognise the antigen and attack it together with the B cell. This does not happen because T cells are able to recognise “self” molecules that are on the surface of B cells. Every person has their own particular "self" molecules, so there are millions of different B cells. They are like personal identity used to identify cells to T lymphocytes. This means that, in the case of organ transplants, T cells can recognise cells that have come from a different body and so help B cells to destroy them. Only identical twins have the same “self”
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