NATURE OF CYTOTOXIC CELLS IN LYMPH FOLLOWING PRIMARY ANTIGENIC CHALLENGE

Efferent lymph from a single lymph node that had been stimulated antigenically with L5178Y mouse lymphoma cells was collected from each of eight sheep. The cytotoxic activity of the washed lymph cells was assayed in terms of their ability to inhibit the growth of lymphoma cells in vitro. The cells from lymph collected between 90-150 hr after antigenic stimulation were highly cytotoxic. The strength of the cytotoxic action correlated with the number of large basophilic lymph cells (immunoblasts) present in the lymph; it is to these cells that we attribute the cytotoxic activity. The cytotoxic action of these cells appeared to be immunologically specific; lymph cells from sheep that had been immunized with bacterial antigens were without cytotoxic activity even though large numbers of immunoblasts were present. Small lymphocytes, as such, whether from immunized or unimmunized sheep, appeared to have no cytotoxic activity. The mechanism of the cytotoxie action is unknown, but in this particular system an important role for specific antibody cannot be excluded. © 1969 by The Williams and Wilkins Co.