Circulating activated suppressor T lymphocytes in hepatitis-associated aplastic anaemia

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Abstract
Lymphocyte subpopulations were measured in the blood of 21 children with severe aplastic anaemia (SAA). Five children with hepatitis-associated AA appeared to constitute a unique group. Compared with children with idiopathic AA, four of five children had a striking increase in percentage of activated suppressor T lymphocytes, which were defined by binding of both anti-Leu 2a and anti-HLA DR monoclonal antibodies (children with hepatitis-associated AA, 21.8 .+-. 19.9% [mean .+-.SD], children with idiopathic AA, 2.9 .+-. 1.2%). However, there was no difference in the mean absolute number of the activated suppressor T lymphocytes between the two groups, because the mean number of lymphocytes was markedly less in children with hepatitis-associated AA (0.28 .+-. 0.06 .times. 109/l) than in those with idiopathic AA (1.64 .+-. 0.74 .times. 109/l). The mean helper: suppressor T lymphocyte ratio was significantly lower in children with hepatitis-associated AA (0.58 .+-. 0.74) than in those with idiopathic AA (1.22 .+-. 0.44). On the other hand, we did not find such a remarkable alteration of lymphocyte subpopulations in children with non-A non-B hepatitis who did not develop AA. These findings suggested that an imbalance of lymphocyte subpopulations and T lymphocyte activation may have pathogenetic relevance in some of the children with hepatitis-associated AA.