Immunoreactive thymosin α1 in human thymus and thymoma
Abstract
Thymosin α1–like immunoreactivity was assessed in human thymus and thymoma tissue extracts by means of a new radioimmunoassay that included an anti-thymosin α1 mouse monoclonal antibody. Thymosin α1–like immunoreactivity levels decreased with age in normal thymuses but not in thymomas. The average thymosin α1–like immunoreactivity level was 45.0 ± 52.1 ng/mg protein in normal thymuses and 273.9 ± 205.0 ng/mg protein in thymomas. The average thymosin α1–immunoreactivity level in thymomas was higher than that in normal thymuses. Thymosin α1–like immunoreactivity levels in thymomas appeared to have no relationship to the clinical stage of the thymoma or associated diseases. When viewed according to histologic characteristics, the average thymosin α1–like immunoreactivity level in polygonal cell thymomas (382.5 ± 192.6 ng/mg protein) was significantly higher than that in the spindle cell thymoma (101.8 ± 81.2 ng/mg protein). When viewed according to the degree of lymphocyte infiltration, thymomas could be classified according to four grades: absent, scant, moderate, and predominant. In predominant or moderate thymomas, the average thymosin α1–like immunoreactivity level was higher than that in scant or absent thymomas. Also, thymosin α1–like immunoreactivity levels in thymuses of patients with myasthenia gravis were relatively higher than those in patients with normal thymuses. (J Thorac Cardiovasc Surg 1993;106:1065-71)