In vitro response of bovine thoracic duct lymphocyte to phytohaemagglutinin following adult thymectomy.

The effect of adult thymectomy on the thoracic duct lymphocyte population of yearling calves has been investigated. Four to 6 weeks after thymectomy animals showed significantly reduced thoracic duct lymphocyte concentrations when compared to non-thymectomized controls. In addition, phytohaemagglutinin responsiveness of thoracic duct lymphocytes, measured by (3H) thymidine uptake, was significantly decreased following adult thymectomy. However, this decreased response to PHA was not accompanied by a change in spontaneous isotope incorporation. It is concluded that adult thymectomy in the bovine probably leads to a reduction in the number of PHA responsive T cells in the thoracic duct lymph.