PAF and haematopoiesis: V. Platelet-activating factor and acetylhydrolase in human femoral bone marrow

ELSEVIER

J. Lipid Mediators

Cell Signailing

12 (1995) 45-47

PAF and haematopoiesis: V. Platelet-activating factor and acetylhydrolase in human femoral bone marrow Y. Denizot a,*, J.L. Charissoux b, N. Nathan ‘, V. Praloran a aLaboratoire

d’Hkmatologie

Exp&imentale,

Faculte’ de Mkdecine, 2 rue Dr. Marcland, 87025 Limoges, France b Service d’Orthop&die Traumatologie, CHRU Dupuytren, 2 Au. M. Luther King, 87042 Limoges, France ’ De’partement d’Anesthesie, CHRU Dupuytren, 2 Au. M. Luther King, 87042 Limoges, France Received

3 January

1995; accepted

1 February

1995

PAF is a phospholipid mediator which is produced from a wide variety of cells and organs. Its levels are regulated by an acetylhydrolase activity found in plasma and tissues (Stafforini et al., 1991). PAF acts both on human haematopoietic progenitors and on mature blood cells (Saito et al., 1992). Results have shown that PAF stimulates the proliferation of guinea-pig femoral bone marrow cells (Kate et al., 1988). We examined the presence of PAF and acetylhydrolase activity in human femoral bone marrow. Ten patients (six women, four men; aged from 44 to 96 years) referred to orthopaedic surgery and without any drug therapy were included in this study according to the Helsinki recommendations. Femoral bone marrow (just under the femoral head) and blood samples were collected on ethanol (80% final) to assess PAF content. PAF was purified on thin-layer chromatography plates, and assessed by the platelet-aggregation assay (Denizot et al., 1995). The assay was sensitive enough to detect levels as low as 100 pg/ml. Plasma isolated from bone marrow and blood samples were collected and stored at - 80” C until assay of acetylhydrolase activity (Miwa et al., 1988). Results are expressed as nmol PAF degraded/ml plasma per min as means of duplicate determinations. Aliquots of bone marrow and blood were used to assess cellular content using a hemocytometer. The different parameters were compared using Wilcoxon tests. The results of the analysis of 10 samples of bone marrow and blood are shown in Table 1. While bone marrow PAF concentrations were significantly (p = 0.01) higher in total bone marrow than in total blood, acetylhydrolase activities in bone

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46 Table 1 Results of analysis

Y. Denizot et al. /J. Lipid Mediators

of bone marrow

PAF AHA Cell number

and blood

Cell S&walling 12 (1995) 45-47

samples

Bone marrow

Blood

P

489 *174 54.8k 6.8 19.3* 4.2

274 k118 58.5& 4.9 6.0+ 0.8

0.01 0.08 0.01

PAF (pg/ml), AHA (nmol/min/ml), and blood. Mean k SE of 10 donors.

and cellular

content

(X lo6 cells/ml)

in femoral

bone

marrow

marrow and plasma were not different (p = 0.08). The cellular concentration was significantly (p = 0.01) higher in bone marrow samples than in blood. No correlation was found between PAF and bone marrow (Y = 0.2, p = 0.57) or blood (r = 0.02, p = 0.94) cell counts. No correlation was observed between acetylhydrolase activity and PAF amounts and the age and sex of patients (data not shown). PAF amounts are significantly higher in femoral bone marrow as compared to blood. These high PAF levels may result from increased PAF production and release rather than decreased PAF degradation as shown by the similar acetylhydrolase activity levels in bone marrow plasma and blood. The presence of PAF in human femoral bone marrow is consistent with the presence of 576 f 39 pg/ml PAF (n = 35) in sternal bone marrow (Denizot et al., 1995), indicating the permanent presence of PAF in active hematopoietic human bone marrow. Furthermore, acetylhydrolase activity is similar in human femur (54.8 + 6.8 nmol/ml per min, II = 10) and sternum (48.0 + 2.3 nmol/min per min, 12= 34) (Denizot et al., 1995). At this time the role of PAF in human bone marrow is unknown. In guinea-pig, PAF stimulates the proliferation of one or some femoral bone marrow cell types through the release of soluble factors (Kate et al., 1988). Such an effect is under investigation in our laboratory. Further studies must be carried out in order to identify the cell type(s) which produce PAF in human bone marrow.

Acknowledgements

We are grateful to the Ligue Nationale Contre le Cancer (ComitC de la Haute-Vienne) and to INSERM (Contrat Normalise d’Etudes Pilotes en Recherche Clinique no. 93CN32) for funding our project.

References Denizot, Y., Trimoreau, F., Dupuis, F., Verger, C. and Praloran, V. (1995) PAF and haematopoiesis. III. Presence and metabolism of platelet-activating factor in human bone marrow. Biochim. Biophys. Acta 1265, 55-60. Kato, T., Kudo, I., Hayashi, H., Onozaki, K. and Inoue, K. (1988) Augmentation of DNA synthesis in guinea pig bone marrow cells by platelet-activating factor (PAF). Biochem. Biophys. Res. Commun. 157, 563-568.

Y. Denizot et al. /J. Lipid Mediators

Cell Signalling 12 (1995) 45-47

47

Miwa, M., Miyake, T., Yamanaka, T., Sugatani, J., Suzuki, Y., Sakata, S., Araki, Y. and Matsumoto, M. (1988) Characterization of serum platelet-activating factor (PAF) acetylhydrolase. Correlation between deficiency of serum PAP acetylhydrolase and respiratory symptoms in asthmatic children. J. Clin. Invest. 82, 1983-1991. Saito, H., Hayakawa, T., Mita, H., Akiyama, K. and Shida, T. (1992) PAF-induced eosinophilic and basophilic differentiation in human hematopoietic precursor cells. J. Lipid Mediators 5, 135-137. Stafforini, D.M., Prescott, S.M., Zimmerman, G.A. and McIntyre, T.M. (1991) Platelet-activating factor acetylhydrolase activity in human tissues and blood cells. Lipids 26, 979-985.