IgM and IgG

What does IgG or IgM mean?

IgG stands for immune globulin G and IgM stands for immune globulin M.  Both are types of antibodies.  IgM is generally produced the first time a host is exposed to an antigen.  IgM will eventually decline, and then the host produces IgG, which lasts much longer.  Detection of IgM indicates acute or primary infection, IgG indicates past infection or immunity. 

From: http://www.dshs.state.tx.us/