This is due to the fact that both tests use different antigens for stimulation.

As with B cells, each type of T cell recognizes a different antigen.

Lymphocytes proliferate and differentiate in response to various concentrations of different antigens.

The great diversity in immune response comes about because there are up to 10 clones with specificities for recognizing different antigens.

Each immunoglobulin class differs in its biological properties and has evolved to deal with different antigens.

Rat/mouse hybrid antibodies can be engineered with binding sites for two different antigens.

There are also two different serotypes found with different antigens that produce unique antibodies.

Each blood type possesses a different antigen with its own special chemical structure.

For each person and each type of cell there are different antigens on the cell's surface.

Each of these variants can bind to a different antigen.