Which immunoglobulin is the most efficient at agglutination?

The most efficient immunoglobulin at agglutination is IgM. This is primarily due to its structure; IgM is a pentameric form, which means it consists of five monomer units linked together. This pentameric structure allows for multiple binding sites, providing a greater capacity to cross-link antigens and to agglutinate particles, such as bacteria or red blood cells.

Agglutination refers to the clumping of cells, and IgM's ability to bind to multiple antigens simultaneously enhances the effectiveness of the immune response. Its size and structure enable IgM to effectively bridge gaps between particles, leading to visible agglutination.

In contrast, other immunoglobulins like IgG and IgA are typically monomeric, which limits their ability to agglutinate targets compared to the larger IgM. While IgE plays a crucial role in allergic responses and defense against parasitic infections, it does not have a primary function in agglutination, making IgM the most efficient in this context.