Leukocyte migration test in subacute thyroiditis: hypothetical role of cell-mediated immunity.

Abstract

There has been a paucity of data employing the leukocyte migration test (LMT) in regard to the role of cellmediated immunity (CMI) in subacute thyroiditis (ST). This has induced us toinvestigate the presence of CMI against subcellular components of human thyroid cells in patients with ST. These subcellular components obtained by the ultracentrifugation method in sucrose discontinuous gradient are: 1) cell membranes, 2) microsomes, 3) membrane-bound ribosomes, 4) mitochondria, and 5) nuclei. Moreover, a crude thyroid extract (CTE) was also used. These subcellular components have been verified by electron microscopy. The LMT technique of Soborg and Bendixen was performed in 22 patients manifesting positive thyroid autoantibody titers in the antithyroglobulin and/or antimicrosomal procedures in the course of their disorder as well as in 10 euthyroid students (volunteers). Different antigenic fractions were tested at the following concentrations [expressed as protein concentration (micrograms per ml) in 1 ml tissue culture medium] 1) membranes, 35 and 140; 2) microsomes, 85; 3) membrane-bound ribosomes, 125; 4) mitochondria, 100; 5) nuclei, 50 and 250; and 6) CTE, 40 and 80. Inhibition in the LMT test in patients with ST was observed using CTE [69 α 13 vs. 90 α 15 (controls); P < 0.001], nuclei (67 α 11 vs. 83 α 11; P < 0.001), microsomes (47 α 9 vs. 89 α 10; P < 0.001), mitochondria (60 α 6 vs. 78 α 7; P < 0.001), and ribosomes (52 α 13 vs. 85 α 20; P < 0.05). No difference from controls was in evidence when the thyroid cell membranes were usedas antigens (80 α 19 vs. 88 α 19; P = NS). The detection of CMI against nuclear, ribosomal, mitochondrial, microsomal,and crude thyroid antigens may well relate to a release of these fractions due to cytolysis brought about by viral infection and destruction.