“…4 In healthy persons, the serum concentration of  2 M is usually less than 2 mg/L, and the urinary excretion is less than 400 g/24 hours. 5,6 Two of the common features among diseases such as human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS), 7,8 autoimmune disorders such as rheumatoid arthritis 9,10 and Sjögren syndrome, 11 and hematologic malignancies including multiple myeloma, lymphoma, and leukemia, [12][13][14][15] are elevated serum levels of  2 M and activation or inhibition of the immune system. In persons infected with HIV, high levels of serum  2 M correlate with the progression to AIDS, 7,8 whereas in the hematologic malignancies, the levels correlate with poor prognosis.…”