Monday, March 8, 2010

What is Passive Immunity?


Passive Immunity
Thus far, all the acquired immunity we have discussed
has been active immunity. That is, the person’s own
body develops either antibodies or activated T cells in
response to invasion of the body by a foreign antigen.
However, temporary immunity can be achieved in a
person without injecting any antigen. This is done by
infusing antibodies, activated T cells, or both obtained
from the blood of someone else or from some other
animal that has been actively immunized against the
antigen.
Antibodies last in the body of the recipient for 2 to
3 weeks, and during that time, the person is protected
against the invading disease. Activated T cells last for
a few weeks if transfused from another person but
only for a few hours to a few days if transfused
from an animal. Such transfusion of antibodies or T
lymphocytes to confer immunity is called passive
immunity.

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