The effects of fractions (chalones) obtained from lymphoid organs on lymphocyte proliferation in vitro

[Humoral factors in the regulation of cell proliferation in haematopoiesis. I. Granulopoiesis and lymphopoiesis (author's transl)]

Humoral Factors obviously play an important role in the maintenance of the steady state in haematopoiesis. There has been work on stimulators and inhibitors for several years. Colony-stimulating factor is the best characterized chemically and biologically. Interest in more or less cell-line-specific stimulators and inhibitors of lymphopoiesis is now growing. Various tissue extracts and cell culture supernatants have been partially purified and characterized biologically and chemically. Monocytes, producing stimulators and inhibitors, have a central function in the regulation of cell proliferation in haematopoiesis. Experiments performed in vitro can help better to understand data so far difficult to explain regarding patients with disturbed haematopoiesis. The in vivo relevance of these experiments, however, remains unclear.

The effects of fractions (chalones) obtained from lymphoid organs on the immune response in vivo

Aqueous extracts of calf and pig lymphoid organs were prepared and fractionated by means of gel filtration, ion exchange chromatography, and isoelectric focusing. These fractions, which had been previously assessed on mitogen-stimulated mouse spleen lymphocytes and other cells in vitro, were tested for their in vivo activity on humoral (haemolytic PFC in mice) and on cell-mediated immunity (skin allograft survival in mice, lymph node weight assay in rats, and systemic GvH-reaction in mice). None of these several fractions elicited either biologically significant or reproducible inhibitory effects. In particular, two fractions, a high and a small molecular weight fraction which were strongly inhibitory in vitro, remained without any chalone-like activity in these in vivo assays. Our results therefore failed to support the existence of a lymphocyte chalone.