ELEVATED CIRCULATING LEVELS OF BETA-2-MICROGLOBULIN IN PATIENTS WITH IDIOPATHIC DILATED CARDIOMYOPATHY

Beta 2-microglobulin is a low molecular weight proein of 11.6 kD found on the surface of nearly all nucleated cells.1 There it constitutes the light invariant chain of the class I major histocompatibility molecule, which is involved in the the antigen presentation during interaction with T lymphocytes.1 Beta 2-microglobulin appears in free soluble form in serum where it is increased in states of T cell activation, i.e., in viral infections,2,3 and chronic inflammatory, autoimmune and lymphoproliferative disorders.4,5 Its serum concentration also depends on renal function because the kidneys are the main site of clearance.6 The marked retention during chronic renal failure results in the formation of the dialysis-associated amyloid whose major protein is β 2-microglobulin.7 Samsonov et al8 recently described β 2-microglobulin as a serologic marker for cellular immune activation in inflammatory heart diseases. We report here that elevated plasma values correlated both with the stimulation of the renin-angiotensin system due to reduced renal perfusion and with T cellular hyperresponsiveness in patients with idiopathic dilated cardiomyopathy (IDC). Thus, β 2-microglobulin reflects different factors in the complex pathophysiology of IDC. © 1993.