Last reviewed dd mmm yyyy. Last edited dd mmm yyyy
IgM is a large pentameric structure, whose higher molecular weight tends to confine it within blood vessels.
Like IgG, IgM is able to combine with antigen and activate complement. It is the first immunoglobulin to be produced following antigenic challenge. Unlike IgG, it does not cross the placenta.
Monomeric IgM, on the cell walls of B lymphocytes, is the major antibody receptor for antigen recognition.
In brief (in adults):
In detail:
Causes of a raised IgM level include:
Causes of reduced IgM levels include:
Reference:
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