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Biomedical subjects

K N Ward

Publications and source records attributed to K N Ward.

44 records · Page 3Linked to original sources
PubMed1987

Opsonisation and phagocytosis of group B meningococci by polymorphonuclear leucocytes: comparison of sulphonamide sensitive and resistant strains.

A large proportion of disease caused by sulphonamide resistant strains of group B type 15 meningococci affects patients 10-24 years. In contrast, disease caused by sulphonamide sensitive strains conforms to the usual pattern, and most infection occurs in early childhood. In an attempt to explain this phenomenon possible differences in susceptibility of resistant and sensitive strains to phagocytosis by polymorphonuclear leucocytes were investigated, using radioactively labelled bacteria. In initial experiments a group B resistant strain required higher concentrations of normal human serum and longer opsonisation times for phagocytosis than an ungroupable non-pathogenic meningococcus. Comparison of sulphonamide resistant and sensitive group B meningococci showed that with either heat inactivated serum or agammaglobulinaemic serum, phagocytosis did not occur with any of the strains, whereas if these two sera were used together, phagocytosis was restored to the level seen with normal human serum. Thus both antibody and complement are required for phagocytosis. Furthermore, opsonisation depended on an intact classical pathway of complement for each group B strain. In all the experiments there was no significant difference between the phagocytosis of sulphonamide sensitive and resistant group B strains neither with regard to the efficiency of opsonisation by normal human serum nor the exact requirements for antibody and complement.

Adolescent↗
PubMed1984

Altered expression of human monocyte Fc receptors in Plasmodium falciparum malaria.

The state of activation of human peripheral blood monocytes was examined by using a rosette assay that detects changes in Fc receptor expression. Monocytes from patients with uncomplicated Plasmodium falciparum malaria showed a significant increase in the number of rosettes relative to healthy controls. In addition, the monocytes from these patients were tested for their ability to phagocytose Candida albicans, but this ability did not differ from that of normal individuals. Finally, the monocytes from patients with cerebral malaria were also tested for Fc receptor expression. In contrast to the results from uncomplicated cases, the activity of the monocytes from these patients was no different from that of controls. We concluded that uncomplicated P. falciparum malaria caused an increase in monocyte Fc receptor expression which did not occur in cerebral malaria and that this difference in activation may be important in the pathogenesis of cerebral malaria.

Adolescent↗
PubMed1981

Helper activity of T lymphocytes which have been stimulated by keyhole limpet haemocyanin in vitro.

Details are given of a system for keyhole limpet haemocyanin (KLH)-induced DNA synthesis by murine T lymphocytes in vitro. Lymph node T cells from mice primed with KLH and Bordetella pertussis were stimulated with KLH under the defined conditions, and it was found that such cultured cells exhibited substantial non-specific helper activity. In contrast similarly primed T cells which had not been cultured showed only antigen-specific help. It is concluded that proper account should be taken of non-specific effects when studying the activity of antigen-specific helper cells in in vitro.

Animals↗
PubMed1979

Non-specific immunosuppressive effects of mouse spleen extracts in vitro.

Cell-free extracts were prepared from the spleens of keyhole limpet haemocyanin (KLH)-primed, ovalbumin (OVA)-primed or unprimed mice, and were shown to suppress non-specifically the secondary antibody response to TNP1000KLH in vitro. Non-specific activity was retained on storage in liquid nitrogen and was not removed by dialysis. These findings are in contrast to those reported elsewhere where it was found that cell-free extracts from the spleens of KLH-primed mice specifically suppressed the IgG response to TNP1000KLH; this discrepancy may well lie in the initial immunological status of the mice used. Nevertheless it is concluded that proper account should be taken of non-specific suppressive effects when studying the activity of cell-free extracts in vitro.

Animals↗
PubMed1978

A modified Marbrook chamber which is cheap and disposable.

The conventional Marbrook culture system has several disadvantages; the preparation and assembly of the chambers is time consuming, the size of the culture vessels limits the number of replicates that may be set up, and placing the cells in the inner chamber is a cumbersome and slow process. We have modified this system by the introduction of a glass ring to make the culture chamber; this is small enough to fit inside a plastic Petri dish which serves as the outer reservoir. The modified Marbrook cultures are easy to manipulate, cheap to produce, disposable, and give comparable results to those obtained with the conventional system.

Animals↗