Reduction of ferricytochrome C may underestimate superoxide production by monocytes.

Superoxide production by stimulated phagocytes is commonly measured by reduction of ferricytochrome C, with specificity of the assay assumed if the reaction is inhibited by superoxide dismutase (SOD). Most preparations of ferricytochrome C contain a small proportion in the reduced (ferro) form, and this is also formed by the reaction of ferricytochrome C with superoxide. The generation of other reactive oxygen intermediates, such as hydrogen peroxide or hydroxyl radical, could cause oxidation of ferrocytochrome C and consequent underestimation of superoxide production. In support of this, it has been demonstrated that exogenous catalase enhanced the reduction of ferricytochrome C by phorbol myristate acetate (PMA)-stimulated human monocytes. Control experiments confirmed that this was due to enhanced detection rather than increased production of superoxide. In addition, SOD was found to promote oxidation of ferrocytochrome C by PMA-stimulated human monocytes, but this was also inhibited by catalase. These effects of catalase and SOD on ferricytochrome C reduction/ferrocytochrome C oxidation were also demonstrated when superoxide was produced independently of monocytes by a xanthine and xanthine oxidase generating system. It is concluded that the assay of superoxide, using 'SOD inhibitable' reduction of ferricytochrome C, underestimates superoxide production.

The clinical value of rapid C-reactive protein measurement in cerebro-spinal fluid.

C-Reactive protein (CRP) has been measured in 90 consecutive CSF specimens using both latex agglutination and an immunoradiometric assay (IRMA). In the 60 CSF specimens otherwise normal by standard biochemical and microbiological criteria, the median CRP level was 32 micrograms/l (95% confidence limits, 0-108 micrograms/l) and in the remaining abnormal specimens the median level was 176 micrograms/l (95% confidence limits, 110-325 micrograms/l, p = 0.001). C-Reactive protein was detected by a commercial latex agglutination kit at a level of approximately 120 micrograms/l and all significant CNS bacterial infections were positive (7 bacterial meningitis, 2 infected shunts). In addition, viral encephalitis, extensive intracranial malignancy and subarachnoid haemorrhage gave positive agglutinations, but not in every case. A further nine specimens with a minor elevation of CRP level were detected by IRMA (median 76 micrograms/l), but this was of little practical significance. We have shown that normal CSF C-reactive protein levels are very low and we conclude that latex agglutination set at a sensitivity of 120 micrograms/l, although only semi-quantitative, is a rapid and useful method to assess CSF C-reactive protein in routine clinical practice and, when positive, is strong supporting evidence for bacterial infection.

Macrophage colony development: properties of colony stimulating factors from murine embryo and pregnant uterus.

Extracts from embryonic and uterine tissue of mice, operationally defined as colony stimulating factor (CSF), promoted the growth of macrophage-granulocyte colonies in vitro. Uterine CSF focusses from pH 5.15 to 6.00 and embryonic CSF from pH 3.60 to 5.20, although both forms have similar biological activity. CSF is relatively resistant to denaturation but it is inactivated by periodate and dithiothreitol. Gel filtration indicates a molecular weight of 45,000 which is unchanged following treatment with insolubilized trypsin, a procedure which affords a useful purification (240-fold). Trypsin-sensitive material in CSF preparations modifies colonial form under certain conditions of culture, probably by increasing the motility of macrophages. Diaminoethane derivatives of CSF were prepared and retained biological activity at isoelectric points above pH 9.0. These derivatives may be covalently linked to Sepharose providing an insolubilized form of CSF to study interactions of CSF with the cell surface.

Characterization of 'e' antigen associated with hepatitis B.

Hepatitis B 'e' antigen (HBe) from the serum of a chronic carrier of HBsAg has been partially purified and characterized. It behaves as an acidic protein, pI 4.5--5.0, which is thermolabile and sulphydryl-sensitive. In serum it usually has a flotation density 1.3 g/cm3, but is sometimes found at density 1.15 g/cm3 because of its association with lipid. HBe from serum is polydisperse on gel filtration although most antigen is recovered with a nominal molecular weight of 3 x 10(5) Daltons. In contrast, in the presence of chaotropic ions, the bulk of serum HBe is found as a species of 3 X 10(4) Daltons previously detected in small amounts under non-dissociating conditions. This suggests that the larger material is formed by non-covalent association of the 3 X 10(4) Dalton species either with itself or other serum components. This would include IgG, although there is no evidence that HBe itself bears immunoglobulin determinants. Analysis of HBe precipitins by polyacrylamide gel electrophoresis under reducing and dissociating conditions suggests that its component polypeptide chains are about 1.7 X 10(4) Daltons.

A serum mannan-binding protein and candidiasis.

A mannan-binding protein purified from rabbit serum agglutinated Saccharomyces cerevisiae in a Ca2+-dependent manner. Its binding to related carbohydrate ligands is reduced either by yeast mannan at 10 ng ml-1 or serum from patients with suspected deep-seated candidiasis. A role for mannan-binding protein in diagnosis and pathogenesis is considered.

Hepatitis B among Indochinese refugees in Great Britain.

Six hundred and thirty-two blood samples from 879 consecutive admissions to one resettlement camp for Indochinese refugees in Great Britain were screened for markers of hepatitis B (HB) virus infection. The overall prevalence of HB surface antigen (HBsAg) was 15%, being 16% in those aged 40 years or less, and falling to 8% in those older than 40 (P less than 0.05). No significant difference in prevalence was found between males and females. HBe antigen was detected in 56% of those with HBsAg and was demonstrable in 55-76% of those under 30 years of age. HBe antibody was found in 21% of HBsAg-positive refugees. In those under 40 years old, HB core (HBc) antibody was commoner in males (P less than 0.01). HBc antibody prevalence increased significantly with age in females (P less than 0.01) but not in males. There was no definite evidence that vertical transmission of hepatitis B was present in the group studied.