Spontaneous Lymphocyte Transformation in vitro: Negative Evidence from a Study of Thymidine Uptake

Abstract

SUMMARY Studies of the uptake of tritiated thymidine by human peripheral lymphocytes cultured in autologous plasma or, after washing, in foetal calf serum have failed to provide evidence for the occurrence of spontaneous blastoid transformation during 1–7 days in vitro. Repeated washing of peripheral lymphocytes caused an inconstant reduction in their ability to respond to stimulation with PHA. The accuracy and sensitivity of the technique of measuring the degree of in vitro transformation activity of lymphocyte cultures by their uptake of radioactively labelled thymidine is increased by partially removing polymorphonuclear leucocytes from the leucocyte suspensions and by restricting exposure of the cultures to the radioactive thymidine to the final 1 hour of culture.

Further Observations on Spontaneous Blastoid Transformation of Human Small Lymphocytes in Vitro

“…When compared to the values obtained in stimulated cultures it can be seen that the control levels are both relatively and absolutely low. This confirms earlier results (Caron, 1967b) that the spontaneou, transformation of human lymphocytes as measured by the total uptake of tritiated thymidine is low in control cultures of up to 7 days duration. However, a slightly higher degree of spontaneous transformation may occur during 7-12 days in uitro (Table 11).…”

“…Johnson and Russell (1965) and Wilson (1966) both found that a high rate of apparently spontaneous blast transformation fell considerably when foetal calf serum was replaced by autologous serum as the protein source in the culture medium. Both Hashem (1965) and Caron (1967b) have shown that when human peripheral lymphocytes are cultured in autologous plasma for 5-7 days spontaneous transformation to the extent described with media containing foetal calf serum does not occur. Caron (1967b) furthermore did not find any increase in the degree of transformation of the control cultures from the subject he studied when these were established in 20 per cent foetal calf serum.…”

“…Both Hashem (1965) and Caron (1967b) have shown that when human peripheral lymphocytes are cultured in autologous plasma for 5-7 days spontaneous transformation to the extent described with media containing foetal calf serum does not occur. Caron (1967b) furthermore did not find any increase in the degree of transformation of the control cultures from the subject he studied when these were established in 20 per cent foetal calf serum. This suggests either that different batches of foetal calf serum differ in their ability to stimulate lymphocyte transformation or that the material may act as a specific antigen in cultures from sensitized individuals.…”

“…In an earlier study (Caron, 1967b) no evidence of spontaneous blastoid transformation was found in human peripheral lymphocyte cultures of up to 7 days duration when this was measured by the ability of the cultured cells to incorporate tritiated thymidine. However, in a subsequent experiment a small number of morphologically typical blastoid cells and a solitary mitotic figure were seen in cell smears from a control culture harvested after 9 days.…”

Peripheral Lymphocyte Populations

“…This parameter parallels mi totic activity in culture [13] and is not affected by the nonspecific 'sponta neous transformation' that occurs [13,14]. Furthermore, the proliferation response that develops in vitro markedly resembles the mitotic wave that follows a secondary response in vivo [3,15].…”