IgM antibodies are the first to appear in the humoral response. They remain intravascular because they are too large to cross vessel walls. They appear soon after stimulation by an antigen. Assaying these antibodies is very often the key element in diagnosing acute infection. IgM levels DECREASE in both total and selective hypogammaglobulinemia (in certain malignancies and in IgG and IgA myeloma) and RISE in polyclonal hypergammaglobulinemic conditions (inflammatory syndromes and hepatitis) like plasma cell dyscrasia (e.g. Waldenstroms macroglobulinemia), benign blood disorders of the elderly and IgM myeloma.
Centrifuge and separate to remove cellular material. Transfer 1 mL CSF