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High Density Lipoproteins (HDL) from three patients with E. coli sepsis contained high, low and no Serum Amyloid Protein (Apo SAA), respectively. Preincubation of neutrophils from healthy persons for half an hour with sepsis HDL as well as normal HDL increased the phagocytosis, the stimulated nitroblue tetrazolium reduction, the chemotaxis and the random migrations of these cells. However, for all these functions, lower values were obtained after incubation with sepsis HDL containing high amounts of apo SAA than with normal HDL. A qualitative change of HDL might thus in part be responsible for the decreased function of neutrophils noted during the acute phase of bacterial infections.

Neutrophilic granulocytes were exposed to an atmosphere of nearly 100% oxygen (hyperoxia) for one hour. The nitroblue tetrazolium (NBT) reduction, reflecting oxygen radical release, was decreased both in resting and stimulated cells, but lysozyme release was unchanged. Short time exposure of patients to oxygen hypertension might therefore be beneficial as therapy, in conditions where reduced production of oxygen radicals is required. The NBT reduction of resting and stimulated neutrophils in an atmosphere of purified argon (hypoxia) was also considerably decreased, and the lysozyme release unchanged. This reflects the anaerobic conditions in abscesses, where the contribution of neutrophil oxygen metabolites to the killing of microorganism might be reduced.

Neutrophilic granulocytes preincubated in vitro with human plasma fibronectin (0-1.25 mg/ml) for 30 minutes showed increased spontaneous and chemotactic migration, increased uptake of fluorescein labelled yeast particles as well as higher NBT-reduction both with and without E. coli stimulation. These effects on the granulocyte functions were found to be mainly dose dependent. In control experiments, no significant effects were noted when fibronectin was replaced by human serum albumin in the same concentration range.

The NBT reduction of granulocytes, increased in the presence of bacteria, was further enhanced bl specific antibody. The enhancement was dose-dependent and increased by complement. Clinically, the NBT test was used for measuring specific antibody in sera from patients after severe infections. With sera from 10 out of 14 patients with proven or suspected septicemia the NBT reduction was enhanced because of the presence of specific antibody. These results correlated well with the bacteriological findings and supported the view that the bacteria isolated from blood were relevant for the disease.

Specific, opsonizing antibodies against Haemophilus parainfluenzae were demonstrated in serum by measuring their enhancing effect on the nitroblue tetrazolium (NBT)-reduction of normal human granulocytes, phagocytizing the homologous bacteria. Patients with septicemia and/or endocarditis and carriers of H. parainfluenzae were studied. In late phase sera of the first group such antibodies were detected in 6 of 9 cases. Opsonizing antibodies against H. parainfluenzae were not detected in any of the carrier sera. A dose-response effect was observed when a positive late phase serum was tested in serial 2-fold dilutions. The enhancement of the NBT-reduction was eliminated by absorption of serum with homologous antigen. The detection of opsonizing antibodies, essential for the immune defense against H. parainfluenzae might be helpful for evaluation of the pathogenicity of this organism, which so far is considered as a rare causative agent.

The effects of purified Salmonella endotoxin (LPS) and of LPS combined with isolated human plasma high density lipoproteins (HDL) on oxidative metabolism, measured by nitroblue tetrazolium (NBT)-test, and on lysozyme release of human granulocytes have been studied in vitro. A considerable increase in the NBT-reduction and in lysozyme release was noted in granulocytes exposed to LPS. The stimulating effect of LPS on NBT-reduction and lysozyme release was significantly diminished when the cells were incubated with LPS together with HDL. These observations suggest that HDL in vivo may play an important part in inhibition of metabolic changes induced in granulocytes by LPS which leads to the production and secretion of tissue damaging mediators.

In 22 consecutive patients with acute viral meningitis we studied the ability of neutrophilic granulocytes to phagocytize yeast particles, the interferon (IFN) levels in serum and cerebrospinal fluid as well as the activity of the enzyme 2'-5' oligoadenylate synthetase in peripheral lymphoid cells. During the acute stage of illness a decreased phagocytosis of the neutrophils was demonstrated, while the adherence of yeast particles to the cells was increased. This was accompanied by the presence of IFN in the cerebrospinal fluid and an increase in the 2'-5' oligoadenylate synthetase activity of peripheral lymphoid cells. About two months after onset of symptoms the synthetase activity and the phagocytic activity of granulocytes were restored to normal levels. The results of this study may indicate that the impaired neutrophil function in viral disease is influenced by increases in IFN levels in vivo.

Bestatin, which is a chemically well-defined immunomodulator, was examined for its possible influence on various monocyte functions. It was observed that pretreatment of separated human blood monocytes with Bestatin did not change their chemotactic or random migration. In addition, the capacity of monocytes to reduce nitroblue tetrazolium or to inhibit growth of Chang cells was unchanged by Bestatin. Phagocytosis of yeast particles, however, was increased by pretreatment of monocytes with Bestatin in vitro and it was observed that oral administration of Bestatin to cancer patients augmented the phagocytic activity of blood monocytes in vitro.

Bestatin, which is a chemically well-defined immunomodulator, was tested for its capacity to change certain functions of human granulocytes from healthy donors in vitro. Pretreatment of granulocytes with Bestatin enhanced their spontaneous migration as well as their migration in the presence of chemotactic stimuli. Moreover, Bestatin treatment augmented the ingestion of yeast particles but it did not change the oxidative metabolism of the cells as measured by their capacity to reduce nitroblue tetrazolium.

Nitroblue tetrazolium (NBT) reduction by polymorphonuclear leukocytes (PMN) has been employed for the detection of specific opsonizing antibodies against Plasmodium falciparum in sera from individuals exposed to malaria parasites. Specific antibody-antigen complex is known to trigger the metabolic activation of normal PMN, as measured by NBT-test. In the sera from 16 out of 17 patients tested the NBT-reduction of normal PMN was, in the presence of P. falciparum antigen, significantly higher than that obtained with pooled normal serum from individuals without malaria background. This enhancement was more pronounced in the presence of complement. NBT-reduction was elevated to a lower extent when human anti-P. falciparum sera were substituted with anti-P. vivax or P. ovale sera. Furthermore, no enhancement was noted when red blood cells lysate was used as antigen. The results indicated the presence of specific opsonizing antibodies against P. falciparum in the patient sera. Oxygen-derived free radicals formed by PMN during the stimulation are suggested as the neutrophil mediated protection against malaria.

Neutrophil leucocyte chemotaxis, phagocytosis and oxidative metabolism were measured in six patients with primary hyperparathyroidism (HPT) who underwent parathyroidectomy. The preoperative neutrophil chemotaxis value was 6.2 +/- 0.3 arb.U. and this decreased to 5.8 +/- 0.5 arb.U. (p less than 0.05) on the third postoperative day and to 5.4 +/- 0.3 arb.U. three weeks later. Serum calcium levels were 2.95 +/- 0.06 mmol/l preoperatively and decreased to 2.20 +/- 0.05 (p less than 0.05) and 2.34 +/- 0.05 mmol/l (p less than 0.05) on the third and 21st day after parathyroidectomy. Phagocytosis measured as the intracellular uptake of complement-opsonized yeast particles by neutrophils was not influenced by operation. In a control group, six patients undergoing hemithyroid ectomy due to microfollicular tumours were studied. In this group leucocyte chemotaxis, phagocytosis and serum calcium levels were not significantly different before and after surgery. Neutrophil oxidative metabolism, measured by the ability of the cells to reduce nitroblue tetrazolium (NBT), was similar in the HPT and control groups both before and after operation. The results indicate that HPT is associated with an abnormal leucocyte migration which is reversed after successful parathyroidectomy.

Different plasma lipoprotein fractions in physiological concentrations have opposite effects on the phagocytosis and migration of human neutrophilic granulocytes. Preincubation for half an hour with very low density lipoproteins decreased the phagocytosis as well as the chemotactic and random migrations of the cells, while preincubation with high density lipoproteins increased the same functions. No effects were seen with low density lipoproteins. It is suggested that disturbances in plasma lipoprotein pattern may affect the function of phagocytes.

19 children who were splenectomized after traumatic rupture and 15 healthy siblings were vaccinated with a 14-valent pneumococcal vaccine (Pneumovax). The serum opsonic activity against types 3, 6A, 7F, 14, 19F and 23F was evaluated before the vaccination and after 2 and 12 months by a new micromethod based on nitroblue tetrazolium reduction of granulocytes. Before the vaccination, opsonic activity was found more often in the splenectomized than in the controls, 38 and 29%, respectively. However, patients and controls responded similarly to the vaccine. The serum opsonic activity changed from negative to positive after vaccination in 31% of the splenectomized, as well as the controls. The results indicate that the protection against pneumococcal infection after vaccination may not be adequate against all pneumococcal types in all patients.