Distribution of lymphocytic subpopulations infiltrated in thyroid glands of Graves' disease

ABSTRACT

We studied ninety cases of thyroid glands both histopathologically and by immunohistochemical methods in patients with Graves' disease using B and T cell markers to evaluate the role of lymphocytic subpopulation. Females were affected more frequently than males with a ratio of 6.5:1, and usually the females were younger than the males at the time of surgery. The heavier the lymphocytic infiltration, the higher was the percentage of germinal center formation or fibrosis. The degree of lymphocytic infiltration was also related to the titers of antithyroglobulin or antimicrosomal antibodies. T cells were mostly scattered individually or in small groups between the follicles; however, in the severely infiltrated group, the major pattern was in clusters. T8 positive cells were more abundant than T4 positive cells, and their distribution pattern was accordant with T11 positive cells. Immunoglobulin synthesizing B cells were positively stained in 47 of 94 cases tested and IgG was the most predominant. In the mild and moderate lymphocytic infiltration groups, IgM was mostly stained at the mantle zone or in the lymphoid cluster of the interfollicular stroma, whereas IgM positive cells were present exclusively in the germinal center of the severely infiltrated group. The results of our study indicate that the major lymphocyte subpopulation in Graves' disease is B lymphocytes, and the degree of T lymphocytic infiltration correlated better with titers of antimicrosomal antibody than antithyroglobulin.