The Cellular Immune Response to Primary Sarcomata in Rats I. The Significance of Large Basophilic Cells in the Thoracic Duct Lymph Following Antigenic Challenge

The cell population in the thoracic duct lymph in specific-pathogen-free rats has been studied following challenge with sheep red cells, B.C.G., fhiorodinitrobenzene, a homograft and a syngeneic tumour where the stimulus was the antigen specific to the tumour. In every case the number of large basophilic lymphocytes— referred to as immunoblasts— in the lymph increased about 3 days after challenge and returned to normal by 10 days. Immunization below the diaphragm gave rise to a greater increase in the number of immunoblasts than immunization above the diaphragm as was to be expected on the assumption that the immunoblasts are released from the antigenically stimulated nodes. From nodes below the diaphragm but not from those above, such cells have to pass through the thoracic duct before entering the blood. The majority of the immunoblasts do not recirculate from the blood to the lymph. The appearance in the thoracic duct of immunoblasts can be used as a measure of the immunological reactivity of the host, whether or not antibody formation and delayed type hyper sensitivity reactions are demonstrable.