Thymus lymphocytes in uraemic rats and the effect of thymosin fraction 5 in vitro.

Cellular immunity of thymus lymphocytes in uraemic rats was studied. Severe and moderate uraemia was induced in rats, and sham-operated and normal rats were used as the controls. As a result, the response of thymus lymphocytes to concanavalin A (Con A) significantly decreased in severely uraemic rats, but did not change in moderately uraemic rats. However, when the thymus lymphocytes were pretreated with thymosin fraction 5, the response to Con A was ameliorated in severely uraemic rats. There was a significant correlation between the effect of thymosin fraction 5 on Con A response and Con A response of thymus lymphocytes. In addition, serum from severe uraemic rats suppressed the response of normal thymus lymphocytes to Con A. These results indicate that severe uraemia may cause an impairment in maturation of thymus lymphocytes, which can be improved by thymosin fraction 5 in vitro.