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Title: Receptors for immunoglobulin G and complement on human eosinophil leucocytes
Author: Abdel Rahman Elawad, Anwar
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1978
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This dissertation is concerned with (1) the identification of surface membrane markers for immunoglobulin G and complement on human eosinophils; (2) how certain pharmacological mediators, which stimulate eosinophil locomotion, influence the expression of these receptors; and (3) the susceptibility of schistosomula coated with antibody and/or complement to killing by human eosinophils, neutrophils and mononuclear leucocytes. By the rosette technique and immunofluorescence it was shown that human eosinophils and neutrophils bear membrane receptors for rabbit and human IgG and the human complement components, C3b, CM and C4. There was a significantly reduced percentage of eosinophils bearing receptors for C4 and C3b when patients with eosinophilia of various aetiology were compared to controls. However, no differences were found with IgG receptors. The ECF-A tetrapeptides (Val-Gly-Ser-Glu and Al.a-Gly-Ser-Glu) and histamine agents previously shown to be preferentially chemotactic for the eosinophil, markedly enhanced the expression of human eosinophil receptors for C3b. The enhancement appeared to be highly selective for the eosinophil since there was no evidence that C3b receptors on neutrophils or monocytes were altered by these pharmacological agents. The mediators similarly enhanced receptors for C4 but under the same conditions Cad and IgG (Fc) receptors were unaffected. A number of other pharmacological mediators including bradykinin and the prostaglandins PGE1, E2 and F2a had no apparent effect on eosinophil C3b receptors. However, a major histamine catabolite, imidazoleacetic acid, also recognised as an anaphylaxis-associated eosinophilotactic agent, enhanced eosinophil C3b receptors to a degree comparable to that of histamine. These results suggested that pharmacological mediators of hypersensitivity may regulate certain eosinophil dependent biological reactions and that there may be a direct relationship between the cell surface 'recognition unit' for eosinophil locomotion and some of the membrane receptors which promote the adhesion of eosinophils to opsonized particles. Studies were also undertaken to determine the susceptibility of schistosomula coated with antibody (Ab) and/or complement (C), to destruction by human eosinophils, neutrophils and mononuclear leucocytes. It was shown that (1) damage to schistosomula in vitro can be mediated by human eosinophils, neutrophils or mononuclear leucocytes in the presence of either 'Ab alone', 'C alone' or 'Ab + C'; (2) the efficiencies of the three experimental systems were Ab + C > C > Ab irrespective of whether effector cells were granulocytes or mononuclear leucocytes; and (3) preferential killing of schistosomula by the human eosinophil, as compared to the neutrophil, was not demonstrable with Ab alone but only when complement was present either alone or in combination with antibody. These studies indicate that the regulation of various eosinophil-associated biological events may be dependent on surface membrane markers, especially those for complement.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available