Question

Where are antigens and antibodies found in blood ?

Answer 1

We are familiar with that antibody is an immunoglobulin protein used by the immune system to identify and neutralize foreign objects such as viruses and bacteria . The antibody recognizes a unique molecule of the pathogen , called an antigen. An antigen is a substance that causes your immune system to produce antibodies against it .

Complete answer: Before inferring about the answer let us first know about antigens and antibodies.
An antibody is a "Y" shaped protein secreted by certain types of white blood cells which have the ability to identify pathogens or infections such as viruses and bacteria . The two tips of "Y" are latched on either pathogen or infected cell at a unique target called the antigen which is also called the antibody generator .
In doing so , the antibody effectively marks the pathogen for neutralization , either by killing it or by preventing it from entering a healthy cell or getting surrounded by other complementary proteins.
Antibodies are produced by white blood cells called B- lymphocytes. During pre- natal or newborn stage of life, antibodies are passed from the mother to the infants through passive immunisation. It is from here a child begins to independently produce antibodies either in the response to specific antigen or as a part of the body's natural immune response.
Humans can produce ten billions of antibodies, each defending against a specific type of antigen. The high variability of the paratope allows the immune system to recognize antigens.
Antigens in blood are carbohydrates that are attached to proteins and lipids. They are produced and found on the surface of the red blood cells and are usually ignored by the immune system. And when we talk about antibodies they are produced by white blood cells and are used up by the immune system to identify and attach the foreign substances in the body.

Note: Vaccines contain antigens which stimulate the B- lymphocytes of the immune system to respond by producing plasma cells which secrete disease specific primary response or antibodies. Some of these B cells are memory B cells that recognize the exposure with the disease in future. This results in a faster and more intense production of antibodies to effectively work to eliminate the disease.