Interleukin-6 is a potent myeloma-cell growth factor in patients with aggressive multiple myeloma.
It has recently been demonstrated that interleukin-6 (IL-6) is a potent myeloma-cell growth factor in the majority of patients with multiple myeloma (MM). Using an anti-bromodeoxyuridine monoclonal antibody (MoAb) to specifically count myeloma cells in the S-phase (ie, labeling index, LI), we demonstrate that the IL-6 responsiveness of myeloma cells in vitro is directly correlated with their LI in vivo. Myeloma cells from all 13 patients with high LIs in vivo (greater than or equal to 1%) responded in vitro to IL-6, the strongest response occurring in cells from five patients with plasma-cell leukemia. In contrast, the cells of only two of eight patients with low myeloma-cell LIs in vivo (less than 1%) responded to IL-6 in vitro. After seven days of culturing with 1,000 U/mL recombinant IL-6 (rIL-6), the median LI value in the first group of patients (in vivo LI greater than or equal to 1%) was 11%, ie 11 times higher (P less than .01) than the median LI value (1%) in the second group of patients (in vivo LI less than 1%). Thus, the in vitro IL-6 responsiveness of myeloma cells is directly related to their in vivo proliferative status, and hence to the severity of the disease.
Zhang
X G
XG
INSERM U291, Montpellier, France.
Klein
B
B
Bataille
R
R
D002455:Cell Division / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6; D007378:Interleukins / Q000494:pharmacology*; D009101:Multiple Myeloma / Q000473:pathology*; D011379:Prognosis; D014407:Tumor Cells, Cultured
D006133:Growth Substances; D015850:Interleukin-6; D007378:Interleukins