Soluble interleukin-6 receptor (sIL-6R), a new prognostic factor in multiple myeloma

sIL-6R is a 55 kD soluble molecule mediating the interleukin-6 (IL-6) signal through the IL-6 receptor-associated transmembrane signal transducer, gp130. It has recently been suggested that sIL-6R serum levels may reflect disease severity in multiple myeloma (MM). We determined sIL-6R serum levels in 25 normal controls (NC) and in 80 MM patients at diagnosis and during the course of the disease. Measurements were done by ELISA. In NC, sIL-6R levels ranged from 14 to 40 ng/ml (median 28 ng/ml) whereas in MM patients the range was 10–200 ng/ml (median 38 ng/ml) ( P  < 0.01). 61 patients entered remission and 19 were resistant. Median sIL-6R value at diagnosis was 36 ng/ml (10–120) in responding patients, and 82 ng/ml (20–200) in non-responding patients ( P  < 0.001). During a follow-up from 12 to 89 months, sIL-6R values remained more or less stable in most patients. High sIL-6R levels correlated with poor survival.     

Origin of Osteogenic Precursor Cells in Extramedullary Marrow Implants

Autologous extramedullary marrow implantation leads to the formation of anodule consisting of bone and hemopoietic tissue. Irradiation of the marrowimmediately prior to implantation withup to 1000 rads does not interfere withthe regenerative process. Since thisamount of radiation is lethal for most ofthe hemopoietic cells the cell initiatingthe regeneration must be more radioresistant and is therefore probably associated with the relatively radioresistantmarrow stroma. When the marrow wasirradiated with 4000 rads 2 wk prior toimplantation it did not regenerate eventhough at the time of implantation itcontained numerous hemopoietic cells.This suggests that the hemopoietic cellsdo not play a significant role in the regeneration of marrow implants.

Submitted on April 14, 1971 Revised on June 15, 1971 Accepted on June 22, 1971