Serum lysozyme and vitamin B 12 binding capacity in myeloproliferative disorders

Intracytoplasmic Lysozyme in Malignant Hematologic Disorders: An Immunoperoxidase Study

Intracytoplasmic lysozynie was studied by the peroxidase antiperoxidase (PAP) and protein A-peroxidase methods in 130 cases of various myeloproliferative and lymphoproliferative disorders and 21 lymph nodes and bone marrow metastases from solid primary tumors. This marker, which can be identified in formalin or Zenker-fixed tissues, as well as in peripheral blood and bone marrow smears, proved useful to distinguish malignant myeloid and histiocytic tumors from malignant lymphoid and undifferentiated epithelial metastases. The diagnostic application of these findings are discussed.

Polycythemia vera megakaryocytes store and release lysozyme to a higher extent than megakaryocytes in secondary polycythemia (polyglobuly)

Lysozyme, a myelomonocytic marker not only exerts bacteriolytic, but also immunomodulatoric properties and was found to bind to the glycosaminoglycan serglycin, an important constituent of the extracellular matrix (ECM). Pathological serum lysozyme levels were described in chronic myeloproliferative disorders (CMPDs) and other hematological conditions. In this context it is remarkable that in polycythemia rubra vera (PV), characterized by a proliferation particularly of the megakaryo- and erythropoiesis, serum lysozyme levels behave independently of the numbers of myelomonocytic cells in peripheral blood. To elucidate whether megakaryopoiesis might be the source of the increased serum lysozyme, we performed an experimental study on isolated and enriched megakaryocytes derived from bone marrow of patients with PV. Findings were compared to a group of patients with reactive (smoker's) polyglobuly (PG). In confirmation of previous results, quantification of serum lysozyme levels showed a slight elevation in the cohort of PV patients which was not correlated with the leukocyte count. Applying an immunohistochemical assay we were able to demonstrate intracytoplasmic lysozyme storage in megakaryocytes. Moreover, performing the reverse hemolytic plaque assay (RHPA), a technique which enables detection of secreted proteins at the single cell level, we found that 54% of the PV, but only 3% of the PG megakaryocytes spontaneously secreted lysozyme. After rhIL-3 treatment the secretion of lysozyme remained unchanged in PV but increased to 14% in PG. These findings suggest that the extent of megakaryocytic lysozyme secretion might discriminate PV from reactive conditions. Although a direct involvement of lysozyme in the regulation of aberrant megakaryopoiesis in PV is not likely, the results of the present study point to the possibility that lysozyme could be involved in the interactions of PV megakaryocytes with ECM. Moreover, the response to rhIL-3 significantly discriminates PV megakaryocytes from megakaryocytes of the PG group.

Distinct lysozyme content in different subtypes of acute myeloid leukaemic cells: an ultrastructural immunogold study

Using an ultrastructural immunogold method, we performed a quantitative study on cellular lysozyme (LZ) content in young normal bone marrow cells and in 14 cases of acute myeloid leukaemia (AML) of the M2, M3, M4 and M5 types. In five cases of M2 we found significantly lower LZ content than in normal promyelocytes and than in nine cases of M3, M4 and M5. In M3, M4 and M5 cells a very high LZ content was observed whereas the serum LZ activity was high in M4 and M5 and normal in M3. The intragranular LZ content was especially high in M5 and in most granules of M4 cells. The immunogold reaction (IGR) for LZ was also performed in cells previously reacted for myeloperoxidase (MPO). In M2 the granules showed definite positive MPO reactivity and low LZ density (granulocytic pattern), whereas in M5 we found high granular LZ content and weak or almost negative MPO activity (monocytic pattern). In M4 we found 'granulocytic' and 'monocytic' type of granules in the same cell. The IGR for LZ performed in post-embedded M5 cells which were previously subjected to phagocytosis of latex particles, showed granules that had moved toward the phagosome, releasing LZ without degranulation. The above findings and those showing normal serum LZ in M3 despite their high cellular LZ content, definitely indicate that only leukaemic M4 and M5 cells secrete LZ into their environment, explaining the high serum LZ observed in those leukaemias.

Limited value of serum ferritin in evaluating iron status in children with protein-energy malnutrition

26 of 46 Nigerian children with protein-energy malnutrition (PEM) had elevated S-Ferritin levels; the geometric mean value in the entire group of children with PEM was 146 micrograms/l and the observed range 11-7000 micrograms/l. There was no statistically significant correlation between the logarithm of the S-Ferritin level and the amount of stainable iron in marrow fragments (r = 0.23; p greater than 0.2). A stepwise multiple linear regression analysis in which the logarithm of the S-Ferritin level was used as the dependent variable and a total of 17 clinical, biochemical and haematological parameters were used as the independent variables showed that 34.8% of the variability in S-Ferritin could be accounted for by variations in the percentage of lymphocytes in the bone marrow. We speculate that the latter parameter may be an index of previous infection and that the elevated S-Ferritin levels may, therefore, be at least partly caused by infections. Increased serum aspartate transaminase activities were also encountered in PEM, suggesting that hepatocellular damage may contribute to the high S-Ferritin levels in this condition. Our data indicate that S-Ferritin has a limited value as an indicator of iron status in subjects with PEM, presumably because of the frequency of infections and of hepatocellular damage in such subjects.

The effects of surgery on the activity of neutrophil granule proteins

Activities of the neutrophil granule-associated proteins beta-glucuronidase, lysozyme and vitamin B12 binding protein were measured, serially, in the cells and serum of 10 patients undergoing total abdominal hysterectomy. The neutrophil leucocytosis which followed total abdominal hysterectomy was accompanied by a fall in the intraneutrophilic activities of all three granule-associated proteins. Intraneutrophilic lysozyme activity and intraneutrophilic vitamin B12 binding capacity were maximally reduced within 4 h of surgery and fell to 62 +/- 13% (mean +/- SEM) and 63 +/- 9% of their preoperative levels, respectively. This contrasted with the activity of intraneutrophilic beta-glucuronidase which was not maximally reduced until 24 h post-surgery when a fall to 80 +/- 6% of the preoperative level was observed. By the fifth postoperative day activities of the three intraneutrophilic granule proteins were increasing and approaching those observed preoperatively. Serum lysozyme and plasma unsaturated vitamin B12 binding capacity (UBBC) rose steadily following surgery and were significantly elevated by the fifth postoperative day. It is suggested that activation and in vivo degranulation of circulating neutrophils may be responsible for these changes in activity of neutrophil granule proteins following surgery.

Immunoreactive calcitonin in leukaemia

A radioimmunoassay was used to measure concentrations of immunoreactive human calcitonin (HCT) in plasma and leucocytes from patients with various leukaemic and myeloproliferative disorders. Plasma immunoreactive HCT concentrations were increased in 32 out of 33 patients with chronic granulocytic leukaemia (CGL) and in all eight patients with acute myeloid leukamia (AML) at presentation or in relapse. Out of 11 patients with other myeloproliferative disorders, eight had increased plasma immunoreactive HCT concentrations. Buffy-coat-cell extracts and culture media from peripheral leucocytes of patients with CGL also contained increased immunoreactive HCT concentrations. In contrast, plasma from patients with chronic lymphocytic leukaemia, acute lymphoblastic leukaemia, and AML in remission had low or undetectable immunoreactive HCT concentrations. Increased plasma and cellular concentrations of immunoreactive HCT may be a consequence of abnormal proliferation of myeloid cells and might prove to be valuable in predicting relapse in patients with myeloid leukaemias.

New aspects of preleukemic disorders

Preleukemic disorders are a controversial group of panmyelopathic disturbances that often precede the emergence of acute myeloblastic or myelomonocytic leukemia. In most instances, these preleukemic disorders are characterized by slowly developing myeloblastosis of the bone marrow. They include preleukemia, primary acquired panmyelopathy with myeloblastosis or smouldering acute leukemia, erythroleukemia, and subacute myelomonocytic leukemia. Sometimes, transitions between these various preleukemic disorders may be observed in a single individual. Abnormalities in cellular differentiation are expressed in cytochemical aberrations and in elaboration of colony forming units by marrow cells of patients with preleukemic disorders. Cytogenic and cellular kinetic abnormalities link preleukemic disorders closely to acute myeloblastic or myelomonocytic leukemia, although in many patients with preleukemic disorders, conversion to acute leukemia is not observed or perhaps not recognized. Understanding pathogenetic and pathophysiological aspects of preleukemic disorders may shed light on aspects of cellular proliferation and cellular differentiation in the acute leukemias.

[Vitamin B12 metabolism of human granulocytes. Differences in vitamin B12 uptake of normal granulocytes and CML leukocytes]

The total cell B12 level in chronic myelocytic leukaemia (CML) is low. The uptake of 57Co-cyanocobalamin by normal granulocytes, lymphocytes and CML leukocytes was studied. It was found that the uptake of vitamin B12 was dependent on its concentration. The velocity of the uptake by CML leukocytes was decreased. The reaction showed a non-competitive inhibition. Lymphocytes had the lowest uptake. Na2EDTA inhibited the vitamin B12 uptake of normal granulocytes.

A method for automatic recording of serum lysozyme activity with the fragiligraph

A quick and simple method for the estimation of lysozyme activity using the Fragiligraph, was described. Diminution of turbidity in a suspension of Micrococcus lysodeikticus produced by the addition of standard lysozyme (hen egg white) or serum sample, was continuously recorded for 5 min by the Fragiligraph. The normal mean serum lysozyme activity value obtained by this method is 6,80 mug/ml +/- 1.85.

Granulocyte release of vitamin B12-binders in vivo and in vitro in leukaemia and non-neoplastic leucocytosis

The unsaturated vitamin B12-binding capacities of the 'large molecular size vitamin B12-binding protein' (LBP) and the 'small molecular size vitamin B12-binding protein' (SBP) were determined by a Sephadex G 150 gel filtration method in 9 patients with chronic myelocytic leukaemia (CML), 5 patients with blast cell leukaemia and 12 patients with non-neoplastic leucocytosis. EDTA plasma and serum separated after 20 min and after 120 min were examined. In the 20 min EDTA plasma samples, the mean LBP value was 8,009 pg/ml in CML, 2,468 in blast leukaemia, 175 in non-neoplastic leucocytosis, and 57 in normal controls. The in vitro release of LBP into serum was much smaller in the leukaemias than in non-neoplastic leucocytosis. No correlation was found between the LBP values and the white blood cell counts or lysozyme values, but lysozyme was correlated to white cell count in CML. It is suggested that the plasma LBP levels reflect the fraction of LBP decay taking place at sites, e.g. the spleen, from which the released LBP can enter the circulation.

The three transcobalamins in myeloproliferative disorders and acute leukaemia

The unsaturated vitamin B12 binding capacity of whole serum (UBBC) and of the three transcobalamins (TC) has been studied in patients with various haematological diseases including myeloproliferative disorders (MPD) and acute leukaemia. The binding capacity of TC I and TC III was increased in MPD; TC I being particularly high in chronic granulocytic leukaemia (CGL) and TC III especially raised in polycythaemia rubra vera (PRV) and in infectious leucocytosis. The binding capacity of both TC I and TC III correlated with blood neutrophil count and the ratio TC III/TC I was low in CGL and increased in PRV. TC II was increased in acute myelogenous leukaemia, during remission and blast cell crisis of CGL and in refractory anaemia with excess of myeloblasts but not in acute lymphoblastic leukaemia (ALL). TC II correlated inversely with blood neutrophil count. There is an inverse ratio between TC II and TC I at least in myelogenous leukaemia. These abnormalities are discussed in relation to granulocyte kinetics. TC III and TC I reflect probably the total body granulocyte pool and share some biochemical and immunological properties supporting the view that they have a common origin in the more mature stages of the granulocyte cell line while TC II probably originates partly in more primitive granulocytes.

The detection of intracellular antigens in human leucocytes by immunoperoxidase staining

An immunoperoxidase procedure is described for staining intracellular leucocyte antigens in peripheral blood and bone marrow smears. Brief exposure of cell smears to a buffered formol acetone mixture was found to give optimal fixation, combining good cellular morphology with preservation of antigenic reactivity. The immunoperoxidase method is superior to immunofluorescence in that it provides a permanent preparation which can be counterstained with orthodox reagents and viewed by conventional light microscopy. In addition the technique is considerably more sensitive than immunofluorescence procedures. Immunoglobulin was demonstrated in plasma cells, Türk cells and a minority of peripheral blood lymphocytes. Lysozyme was found in cells of the neutrophil series from promyelocytes to mature granulocytes. Monocytes stained for lysozyme but the reaction was less intense than in neutrophils and some monocytes were devoid of activity. Lactoferrin stained strongly in mature neutrophil polymorphs and metamyelocytes, but was weak or absent in earlier myeloid cells. These reaction patterns are in keeping with previous reports on the distribution of these antigens in human leucocytes. In the case of immunoglobulin and lysozyme it was possible to abolish leucocyte staining by incubation of the specific antisera with the appropriate purified antigen, providing additional proof of the specificity of the reactions. Anti-ferritin antisera stained granulocytes and myeloid precursors strongly, and reached weakly with a minority of monocytes. These latter observations are not entirely in accordance with published data on the leucocyte distribution of ferritin and may be attributed to antibody activity of unknown specificity in the anti-ferritin antiserum.

Neutrophil kinetics in corticosteroid induced neutrophilia measured by plasma lysozyme

A single dose of prednisone (2 mg/kg orally) resulted in a mean rise in neutrophil counts to 2.3 (range 1.5-3.6) and a mean decrease in plasma lysozyme to 0.73 (range 0.50-0.87) times the value before the steroid was given in 10 haematologically normal persons. There was no change in the intraneutrophilic lysozyme activity. It is concluded that the decrease in plasma lysozyme is compatible with a reduction in the egress of neutrophils to the tissues and a decrease in the neutrophil turnover rate.

Serum levels of lysozyme in term and preterm newborns

Serum lysozyme levels were studied in term babies at the time of delivery and again between 7th and 30th postnatal days, and in preterm babies on the 1st, 3rd, and 5th postnatal days. Levels in term babies at delivery (mean 2.28 mug/ml) were similar to those found in adults, but they fell between the 7th and 30th postnatal days. In premature babies lysozyme levels on the first day of live (mean (0.82 mug/ml) were lower than in term babies. They tended to rise during the first 5 days, by which time they had reached levels found in term babies between the 7th and 30th days. The low lysozyme levels in preterm and in term babies after the first few days of life may contribute to the poor ability of the newborn baby to localize infection and to kill bacteria extracellularly.

Indices of granulocyte activity in inflammatory bowel disease

In conditions with increased neutrophil production, the serum total vitamin B(12)-binding capacity (TBBC) is considered to correlate with the blood pool size of neutrophil granulocytes. The serum lysozyme, on the other hand, is a measure of neutrophil (and monocyte) turnover. The mean serum TBBC was significantly raised in patients with ulcerative colitis (range 1.23-5.51 ng/ml; mean 2.64 ng/ml) and patients with Crohn's disease (range 1.58-9.29 ng/ml; mean 2.93 ng/ml). The elevated values were shown to be due to rises in the granulocyte-secreted binding proteins, transcobalamins I and III. The TBBC was shown to rise with increasing activity of disease and to correlate roughly with the blood neutrophil granulocyte count. Patients with inflammatory bowel disease also had a significantly raised mean level of serum lysozyme (range 3.1 to 10.4 mug/ml; mean 6.8 mug/ml), but there was no correlation in individual patients between serum lysozyme and total B(12)-binding capacity. These results are taken to indicate an enlarged granulocyte pool and increased granulocyte turnover in inflammatory bowel disease.