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C J Clarke

Publications and source records attributed to C J Clarke.

42 records · Page 3Linked to original sources
PubMed1991

Mucosal priming of T-lymphocyte responses to fed protein antigens using cholera toxin as an adjuvant.

Cholera toxin is widely recognized as a potent stimulator of mucosal IgA responses after oral feeding. However, comparatively little is known of its ability to stimulate cellular responses. This is due in part to the direct inhibitory effects of cholera toxin on T lymphocytes, which can confound attempts to study primed T-cell responses in vitro. We have avoided this problem by using cholera toxin as an adjuvant to enhance the response to an unrelated protein fed simultaneously. Thus the simultaneous feeding of 10 micrograms of cholera toxin and 5 mg of keyhole limpet haemocyanin (KLH) results in the priming of T cells in the spleen, mesenteric lymph nodes, Peyer's patch and lamina propria that proliferate when restimulated with KLH in vitro. The feeding of KLH alone does not result in such responses. Both CD4- and CD8-positive antigen-specific T cells were involved in the response and the cells produced both interleukins 2 and 4 on antigen restimulation in vitro.

Adjuvants, Immunologic↗
PubMed1990

Whole cholera toxin and B subunit act synergistically as an adjuvant for the mucosal immune response of mice to keyhole limpet haemocyanin.

Cholera toxin (CT) is a potent stimulator of IgA responses when administered orally and has been shown to promote IgA responses to a second protein such as keyhole limpet haemocyanin (KLH) if this is fed simultaneously. In this paper we show that whilst feeding 5 mg KLH with either 0.5 micrograms CT or 10 micrograms B subunit fails to stimulate a mucosal IgA response to KLH, feeding 0.5 microgram CT and 10 micrograms B subunit together with 5 mg KLH produces a local IgA anti-KLH response as great as that produced by 10 micrograms of whole CT. In addition to stimulating IgA responses in the lamina propria, preliminary results indicate that cellular responses are also stimulated, as we have demonstrated KLH antigen-driven proliferation of cells isolated from groups of mice fed either 10 micrograms CT + 5 mg KLH or 0.5 micrograms CT + 10 micrograms CTB + 5 mg KLH but not mice fed KLH alone or with either 10 micrograms CTB or 0.5 micrograms CT. These results indicate that the mucosal adjuvant action of CT is due to a synergistic effect involving both the GM1 binding of the B subunit and adenylate cyclase activation by the A subunit.

Adenylyl Cyclases↗
PubMedDate not supplied

Altered intestinal macrophage phenotype in ovine paratuberculosis.

The expression of macrophage surface markers that are likely to be important in antigen presentation and cell interactions was examined in normal sheep and those with clinical paratuberculosis. Immunohistological studies demonstrated that intestinal macrophages in diseased sheep expressed MHC class II, LFA-1 and CR4 antigens weakly compared with normal tissues. Reverse transcriptase-polymerase chain reaction analysis of MHC class II mRNA in intestinal whole tissue samples showed no significant difference between control and diseased groups. A reduction in molecules such as MHC class II and LFA-1 on the surface of infected macrophages could have implications for survival of the intracellular mycobacteria and the persistence of infection.

Animals↗
PubMedDate not supplied

Comparison of the absorbed ELISA and agar gel immunodiffusion test with clinicopathological findings in ovine clinical paratuberculosis.

Thirty-two sheep with clinical paratuberculosis and 43 normal, healthy control animals were tested for serum antibodies to Mycobacterium avium subspecies paratuberculosis with the absorbed enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) test. All the sheep were necropsied and the diseased cases were categorised as having either multibacillary ('lepromatous') or paucibacillary ('tuberculoid') intestinal lesions. The ELISA and AGID test were highly sensitive when testing the multibacillary group (86.4 per cent and 100 per cent, respectively) but the sensitivity of the tests in the paucibacillary group was significantly lower (10 to 50 per cent and 30 per cent, respectively). These findings were related to the ELISA optical density readings, with the multibacillary samples having values significantly greater than those of the paucibacillary and control groups, and the optical density values appearing to correlate with the numbers of mycobacteria present in the intestinal lesions. These results indicate both the usefulness of serological testing in the diagnosis of the multibacillary form of paratuberculosis and the difficulty in identifying animals with the paucibacillary form of the disease.

Animals↗