A Lymphocyte-stimulating Factor produced in vitro

Abstract

Bain, Vas and Lowenstein¹ have recently reported that when peripheral leucocytes of two individuals are cultured together, some of the cells enlarge and undergo mitosis. Bach and Hirschhorn² have further shown that not only intact cells, but also extracts of leucocytes, disrupted by freezing and thawing, could stimulate cells to divide. Experiments reported in this communication demonstrate that cell-free media obtained from leucocytes in culture contain mitogenic factor(s), and suggest that these factors might be produced by the cells in vitro.