By linking these outer coats to proteins (e.g. toxins), the immune system can be led to recognize the polysaccharide as if it were a protein antigen.

Adjuvants are generally used with soluble protein antigens to increase antibody titers and induce a prolonged response with accompanying memory.

The size, extent of aggregation and relative nativity of protein antigens can all dramatically affect the quality and quantity of antibody produced.

Investigators should also consider the status of nativity of protein antigens when used as immunogens and reaction with antibodies produced.

Polysaccharide antigens tend to induce more IgA2 than protein antigens.

MART-1/Melan-A is a protein antigen that is found on the surface of melanocytes.

Once born, a child's immune system responds favorably to protein antigens while not as well to glycoproteins and polysaccharides.

Also, tomatine is known to be an immune adjuvant in connection with certain protein antigens.

Certain microbial molecules, such as viral nucleotides and protein antigens, can elicit an immune system response against invading pathogens mediated by signal transduction processes.

It is also required for induction of cytotoxic immunity by vaccination with protein antigens, for example, tumour vaccination.