Augmented mitotic response of human peripheral lymphocytes in the presence of lymphocytes from nude mice: detection of a small number of functional human lymphocytes in the explanted host.

In the present paper, authors showed a method to detect a small number of functional human peripheral lymphocytes (HPL) in the presence of lymphoid cells of nude mouse (n-ML). HPL was mixed with n-ML to give a total number of 5 X 10(4) cells and cultured in vitro in the presence of PHA for 5 days. HPL responded will to PHA while n-ML did not, as assessed by 3H-TdR incorporation in the presence of the mitogen. Synergistic response between these two cell population was observed. Five--ten folds enhancement was shown by mixing 5 X 10(3) HPL and 4.5 X 10(4) n-ML (10% of HPL) and 500 HPL became detectable by comixing with n-ML, while 5,000 HPL was the lowest limit to be detected in a single cell culture with this mitogen. The results seem to indicate that this method could detect functional HPL as small number as one percent of the cell mixture. On the other hand, xenogeneic mixed lymphocyte reaction was observed when the percentage of HPL exceeded 40%. Mitomycin-C treatment of either HPL or n-ML revealed that a major part of cells incorporating 3H-TdR was HPL which could be activated by the stimulation with xenogeneic murine nucleated cells and that a smaller part of murien B cells were also stimulated by the HPL.