Myelodysplastic syndromes (MDS) are clonal haematological disorders and MDS neutrophils have various abnormal functions which cause an increased risk of infective mortality. We examined ...luminol-dependent chemiluminescence and cytoplasmic Ca2+ increase in order to characterize the mechanisms of a signalling defect in MDS neutrophil respiratory burst. In MDS patients, chemiluminescence stimulated with N-formyl-L-methionyl-L-leucil-L-phenylalanine (FMLP) and calcium ionophore A23187 was defective (17.2 +/- 13.7 v 44.3 +/- 16.6, P = 0.001; 42.2 +/- 21.3 v 82.0 +/- 23.6, P < 0.05, respectively), but phorbol 12-myristate 13-acetate (PMA) chemiluminescence was normal (73.4 +/- 26.9 v 79.5 +/- 23.8, P = 0.52). There were no statistical significances in cytoplasmic Ca2+ increase stimulated with FMLP and recombinant human interleukin-8 (rhIL-8) compared with controls (251.1 +/- 104.3 v 272.7 +/- 41.2, P = 0.295; 238.6 +/- 65.0 v 253.9 +/- 38.3, P = 0.567, respectively). Flow cytometric analysis of MDS neutrophils disclosed that most MDS patients showed normal neutrophil cytoplasmic Ca2+ response to FMLP and rhIL-8. However, two patients with refractory anaemia with excess of blasts displayed a significant decrease of both chemiluminescence and cytoplasmic Ca2+ response to FMLP, and they also displayed low expression of FMLP receptor. These data suggest that most MDS patients have low FMLP chemiluminescence which is not due to a defect in the FMLP receptor. It is proposed that defective FMLP chemiluminescence in MDS results from a putative defect in protein kinase C- and Ca(2+)-independent cell-signalling mechanisms. Only a small group of patients have numerical or structural defects in the FMLP receptor, causing significant decrease of neutrophil respiratory burst.
The A or B-glycosyl transferases of hematological diseases showed low activities in the majority of malignant diseases, and their activities became to normal during recovery and remission of the ...disease. In the cases of leukemia accompanied with A or B-red blood cell type changes, the glycosyl transferases were also low. There was one exception having a loss of A-red blood cell antigen with normal level of A-transferase. These findings suggest that there are other factors which cause red blood type change. For example; H-transferase decrement, abnormal proliferation of erythrobasts in addition to A or B-transferase decrement.
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