[The relationship between serum IAP and peripheral K cells in patients with subacute thyroiditis]

In a previous study, we showed that the percentage of peripheral K cells of patients with subacute thyroiditis (SAT), determined by a plaque-forming cell technique, was significantly lower than that of normal controls, and that ther sera from SAT significantly inhibited the activity of K cells in normal lymphocytes, suggesting that in the sera of SAT there is some factor which inhibits K cell activity. In this study, we investigated the relationship between K cells and the serum immunosuppressive acidic protein (IAP), the sex difference in percentage of K cells, and the absolute count of K cells in patients with SAT. In normal controls, there was a sex difference in the percentage of K cells in total lymphocytes; the percentage was significantly lower in women (mean +/- S.D., 5.0 +/- 2.0%; n = 12; p less than 0.01) than in men (8.4 +/- 2.9%; n = 20). However, there was no sex difference in the absolute count of peripheral K cells. In the acute phase of SAT, the percentages of K cells wee 2.4 +/- 1.8%; 2.4 +/- 1.9% and 2.7 +/- 1.0% in 19 patients, 16 females and 3 males, respectively, which were significantly lower than 6.8 +/- 3.0%, 5.0 +/- 2.0% and 8.4 +/- 2.9% in 25 controls, 12 females and 13 males, respectively. The absolute counts of K cells in the acute phase of SAT were 56 +/- 45/mm3 and 58 +/- 48/mm3 in 13 patients including 11 females, respectively, which were significantly lower than 165 +/- 63/mm3 and 153 +/- 73/mm3 in 12 patients including 5 female controls, respectively. It was observed that serum IAP values in SAT were correlated negatively with the percentage of K cells and positively with the inhibition rate of SAT sera on K cells from normal subjects. Moreover, purified IAP showed a dose-related inhibition on the K cells from the control subjects. These results suggest that IAP in the sera of SAT seems to be one of the factors which inhibits the activity of K cells.