I took my dat today there was actually a question regarding the role of a specific Immunoglobulin.
I memorized them quite quickly by associating a scenario for each one according to their name:
IgM: I imagined someone saying "MINEE" and rushing to some place to claim something. (IgM: are usually first responders)
IgG: "Ginormous"(IgG is most abundant so i just associated being large to having a lot of something)
IgE: "Allergieeeeeeeeeee" (IgE bind to allergens etc)
IgA: "Waaaaaaa" I imagined someone crying and just exaggerated the aaaa part in my head. (IgA is in tears/mucosal lining)
IgD: D sounds like B. (IgD is found on surface of B cells)
I know some of these are stupid haha but it helped me memorize it super quickly.