Final answer:
Polysaccharides are most immunogenic when attached to proteins or lipids, forming B. glycoproteins and glycolipids, which are important for cell recognition and immune response.
Step-by-step explanation:
Polysaccharides are most immunogenic when attached to proteins or lipids, or when associated with cells. In the body, these molecules typically conjugate with proteins and lipids to form glycoproteins and glycolipids, respectively. For instance, red blood cells have different types - A, B, AB, or O - dictated by the specific oligosaccharides attached to their membranes. These oligosaccharides not only define the blood type but also play crucial roles in cell recognition and immune response.
This immunogenicity is a key factor taken into account in vaccine development, such as in the case of conjugate vaccines. The efficacy of these vaccines is enhanced by attaching the polysaccharide antigen to a protein, which significantly improves the immune response, particularly in young children. The recognition function of carbohydrates on the cell surface is essential for the immune system to differentiate between self and non-self entities, which is critical for the prevention and response to infectious diseases.