|Questions About Lectins|
Lectins Versus Antibodies
What is the difference between a lectin and an antibody?
Although often considered 'plant antibodies,' lectins are too varied a class of molecules to say that there is any rhyme or reason to their structure. In essence, a lectin is any protein molecule capable of binding to carbohydrates. Thus they can come in a mind-numbing variety of shapes and sizes: from huge molecules like the lectin from Helix pomatia (snail) to very tiny molecules, such as the lectin found in wheat germ.
On the other hand, antibodies are manufactured by the immune system, and other than a small portion of the molecule which is 'variable,' they are very homogenous (i.e similar to each other).
An antibody is usually made in response to an infection or innoculation. Lectins are pretty much made continuously.
Antibodies also tend to be developed against proteins, unlike lectins which tend to specifically attach to carbohydrates.
Both lectins and certain antibodies are capable of causing agglutination (the process of cells interlinking together). However, not all antibodies are agglutinins. Only the class of antibodies call IgM antibodies can cause agglutination, and interestingly, this is the class of antibodies we make against other blood types (which is why our 'anti-other blood type' antibodies are called 'iso-hemagglutinins'.)
To obfuscate things even a bit more, we often make antibodies to dietary lectins!