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A case of acute myeloid leukaemia (AML) (M2 type) is described in which the neutrophil population contained markedly increased peroxidase activity. The increased peroxidase activity was initially detected during routine counting with the Hemalog D automated differential counter and the increased enzyme staining was confirmed by manual and ultrastructural cytochemistry. The abnormal neutrophil population persisted after blast cells had disappeared from the blood and until marrow hypoplasia was induced by chemotherapy. When remission emerged, the peroxidase activity of the neutrophil population was normal. At subsequent relapse, the neutrophil population with increased peroxidase activity reappeared and with the induction of second remission neutrophil peroxidase again returned to normal. In 8 other cases where sufficient neutrophils were present for analysis by the Hemalog D, neutrophil peroxidase was normal or not increased in 7 cases, but was markedly reduced in 1 case of AML (M6 type). It is suggested that abnormalities of neutrophil peroxidase activity detected by the Hemalog D may serve as useful leukaemic markers.

The phenomenon of giant anomalous lysosome formation in human Chediak-Higashi syndrome leukocytes was analyzed. Ultrastructure findings combined with cytochemical procedures for visualizing acid phosphatase and peroxidase activity showed giant anomalous granules in addition to normal, small and enlarged granules. Massive granules in lymphocytes had an appearance and structure different from those found in other leukocytes. The giant granules seem to be a product of an active fusion between primary and secondary normal sized or enlarged lysosomes. This fusion occurs in polymorphonuclear neutrophils, eosinophils and in monocytes. No fusion was found in lymphocyte granules.

Neutrophil peroxidase activity was determined before delivery in 46 pregnant women. 36 of these women were also tested on the 1st day and 30 on the 3rd day after delivery. A significant increase in the average values of neutrophil peroxidase activity was found in all parturients as compared with the controls. The highest peroxidase activity was observed before parturition. The possible mechanism of these changes is discussed.

A 72-year-old man with refractory anemia (RA) developed overt megakaryoblastic leukemia after the course of RA with excess of blasts. The blasts were positive for platelet peroxidase activity and had platelet glycoproteins (GPs) such as GPIIb/IIIa and GPIIIa. The bone marrow biopsy at terminal stage disclosed marked fibrosis. The nature of the megakaryoblasts was investigated. The blasts did not differentiate morphologically into mature megakaryocytes with TPA addition. In vitro colony assay showed the failure of colony-forming unit, megakaryocyte growth in peripheral blood. The pathogenesis of myelofibrosis in our patient is discussed.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a major cause of severe neonatal jaundice in Nigeria, but not all G6PD-deficient babies become jaundiced. Neonatal jaundice not attributable to G6PD deficiency nor to any other known aetiology is also common. In an effort to explain these two facts, we have measured the levels of the three enzymes G6PD, glutathione peroxidase (GSHPX), and glutathione reductase (GSSGR) in 38 jaundiced newborns, 26 control newborns, and 44 normal adults, all of them males. We could not yet prove an additive effect of GSSGR or GSHPX deficiency with G6PD deficiency in causing jaundice. There was no evidence that low levels of GSHPX per se are associated with jaundice. However, jaundiced newborns with normal G6PD had significantly lower levels of GSSGR than control newborns with normal G6PD. These data suggest that a relatively low activity of GSSGR, a riboflavin-dependent enzyme, may predispose the red cells to accelerated destruction in the neonatal period.

Five cytochemical reactions in current use (MPO, PAS, LAP, SB and EST) were operated on 180 children aged 1 month to 6 years, divided into three age groups (less than 12 months, 1-3 years and 3-6 years). No significant differences are apparent from one group to another, and the mean values are identical with those of adults. On the other hand, certain variations are evident in comparison with the scores of newborn children: important decrease in LAP, increase in SB, EST and PAS. These tests should be done in investigations of inborn metabolic errors, chromosome anomalies, blood diseases, and defects in defense mechanisms.

Automated cytochemistry by the Hemalog D carries out leukocyte differential counts in a continuous flow mode on whole blood EDTA-collected samples, through the optical measurement of enzyme activity and cell size. This operative principle thus parallels the basis of the FAB classification of acute leukemias. Although the cell classification logic system can be misled by the heterogeneity of most leukemic populations, valuable qualitative information may be obtained from the x-y oscilloscope display. This provides a true morphological representation of the leukemic cell distribution. According to such a preliminary assumption, each FAB subtype of acute leukemias is shown to reproduce a peculiar image of cellular distribution when analyzed by the Hemalog D.

The structure of human eosinophils genetically lacking peroxidase is described. Structural changes were discerned in the specific granules of the deficient eosinophils as compared to normal eosinophils. Apart from the inhibition of peroxidase formation, this mutation also affects the structure of the specific granules - primarily the interrelationship between the matrix and the core.

It was found that neutrophils in untreated uraemic patients as well as in subjects on regular dialysis treatment displayed higher activity of acid phosphatase, alkaline phosphatase and peroxidase. Spontaneous reduction of nitro blue tetrazolium (NBT) by granulocytes was also higher in both groups in comparison to controls. Stimulation with latex particles gave similar results of NBT reduction in investigated patients and controls. Lymphocytes also showed an increase in acid phosphatase activity if compared to healthy persons. It seems possible that granulocytes which take part in unspecific defense mechanisms are more active in uraemic patients due perhaps to subclinical infections.