RESUMO
Leptin is a nonglycosylated protein produced mostly by adipocytes. The role ofleptin in body weight regulation through its anorectic effect in hypothalamus is very well known. Less known are other leptin effects such as the stimulation of hematopoesis and some parts of immunity system. The role of leptin in the pathogenesis of some malignant tumors is discussed. Only a little is known about bone marrow adipocyte leptin production. We examined leptin concentrations in the sera from peripheral blood and bone marrow, the percentage of bone marrow fat, the degree of bone marrow infiltration, the body mass index (BMI) in 42 patients with lymphoproliferative diseases. We found that bone marrow has significantly lower leptin levels (6,6+/-10,9 ng/ml) than peripheral blood (9,1+/-11,5 ng/ml) (p < 0.0001). Bone marrow and peripheral blood leptin levels have also a significant thin correlation (r = +0.91, p < 0.0001). Bone marrow (r = +0.55, p < 0.0005) and peripheral blood (r = +0.52, p < 0.0005) leptin concentrations are significantly correlated to BMI. Blood serum leptin (r = +0.46, p < 0.003) and bone marrow leptin (r = +0.40, p < 0.01) are related to the bone marrow fat percentage. In addition we found a negative correlation of blood serum leptin (r = -0.59, p < 0.0001) and bone marrow leptin (r = -0.42, p < 0.005) to bone marrow malignant infiltration. When we divided the patients into groups with bone marrow infiltration more than 10% and without or less than 10% infiltration, the first group had significantly lower peripheral blood (p < 0.001) and bone marrow (p < 0.02) leptin. We also confirmed a relation of bone marrow fat and infiltration (r = +0.49, p < 0.001). Our results suggest a relationship among leptin levels in blood or bone marrow and bone marrow infiltration in lymphoproliferative diseases. This fact needs further investigation and an evaluation of its application in clinical practice.