In this video, we're going to talk more about the details concerning the IgG class of antibodies. The IgG antibody is considered the standard antibody in our system. This is because the IgG antibodies are the most abundant antibody class in our blood and tissues. In some individuals, IgG antibodies can make up to 80% of all immunoglobulins.

These IgG antibodies have a variety of functions. They are capable of binding to very specific antigens and can eliminate pathogens by activating the complement system's classical pathway, which, recall, we covered when we discussed innate immunity in our previous lesson videos. IgG antibodies are also known for providing immunity to a developing fetus during pregnancy, as well as to a newborn child after birth. This is due to their remarkable ability to cross the placenta between a mother and her baby, allowing the mother's IgG antibodies to protect the baby. Essentially, the mother is protecting the baby with her antibodies.

IgG antibodies are also known for having a long half-life, meaning they are very stable and can last a long time within our bodies before being broken down. This long half-life extends the duration of protection for a newborn through the first few months after birth until the baby is capable of generating its own antibodies. Essentially, a mother's antibodies protect the baby while it is a developing fetus, and for the first few months of the baby's life, until it can produce its own antibodies.

Looking at our image below, you will see it highlights the important features of the IgG class of antibodies. It showcases the standard antibody structure we discussed in previous lesson videos, and emphasizes that IgG is the most abundant class of antibodies, making up about 80%. It also highlights the role of IgG in providing infant immunity during and after pregnancy because of its ability to cross the placenta. Finally, this IgG antibody has various immune functions, including the ability to activate the complement system via the classical pathway, where it can bind to antigens. This activation leads to different types of complement system activities such as inflammation, opsonization, and cell lysis of microbes.

If you do not remember the details about the complement system classical pathway, I encourage you to review our older lesson videos on that topic. But for now, this concludes our brief lesson on the IgG class of antibodies. As we move forward in our course, we will also discuss some of the other classes of antibodies. I'll see you all in our next video.