Heterogeneity of monocytes in HIV patients

Abel, Philippe Michel (1993) Heterogeneity of monocytes in HIV patients. MSc(R) thesis, University of Glasgow.

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Abstract

Monocytes from human immunodeficiency virus type 1 (HIV-1) infected patients have an increased heterogeneity of phenotype and function. The phenotype of peripheral blood monocytes was characterized by flow cytometry using monoclonal antibody markers against various surface antigens. The functional aspect of monocytes in vivo was investigated by measuring plasma interleukin-6 (IL-6) in HIV-infected patients to see if this cytokine correlated with any other parameters in the blood. This was followed by a study of the cytokines gene expression in peripheral blood monocytes. The accessory cell function of monocyte, was looked into by considering the effect of monocyte-derived prostaglandin E2 (PGE2) on lymphocyte proliferation, and monocyte interleukin-1 alpha (IL-1alpha) and tumour necrosis factor alpha (TNF-beta) production, in anti-CD3 stimulated whole blood cultures of HIV-l-infected patients. Light microscopy study of peripheral blood of HIV patients showed large mononuclear cells whose identity was difficult to distinguish morphologically. In contrast, flow cytometry study using monoclonal antibodies to CD 14 antigens, revealed these cells to be monocytes. Monocyte numbers in the peripheral blood of HIV patients, based on anti-CD14 staining, showed no significant difference with disease progression. However, because of a progressive reduction in total white cell count, there was a significant increase in the proportion of these monocytes with disease progression (p < 0.05). Patients showed no significant difference in monocyte numbers compared to controls. However, the proportion of monocytes in patients ((median and interquartile range; 14.0 (8.8-18.5%)) showed a significant increased compared to controls (8.0 (7.0-12.3)%), (p < 0.05). Monocyte membrane CD4 expression was significantly decreaseed with disease progression (p < 0.01), in parallel with T-cell CD4 expression. Flow cytometry showed that a proportion of monocytes could be heterogeneous, showing an extra discrete subset of cells which were larger, and expressed phenotypic evidence for activation or maturation. These large monocytes had increased expression of the markers CD1lb, HLA-DR, CD45 and CD16, some of which suggested cell activation. The approach devised in this thesis to examine proliferation by CD25 expression allowed the simultaneous measurement of cytokines and PGE2 in culture, which would not have been possible using the harvesting techniques of traditional tritiated thymidine incorporation. The patients' responses to anti-CD3 were divided into three groups; those with either negative, poor or good responses. Monocyte PGE2 levels in cultures were found to correlate inversely with the lymphocyte responses in HIV- infected patients. Patients with negative responses had high levels of PGE2, while patients with good responses had low PGE2 levels. This suggested the hypothesis that high constitutive PGE2 synthesis by monocytes in HIV patients contributed to the reduced lymphocyte proliferation which is seen in disease progression. IL-1alpha and TNF-beta in some culture supernatants were found to increase with the lymphocytc proliferative response. Both cytokines showed high post-stimulation levels, however some patients showed a low spontaneous TNF-beta production in vivo. These observations suggested that there exists a more dynamic situation of recruitment, activation and maturation of peripheral blood monocytes driven by HIV infection, which results in a broader phenotypic profile. Peripheral blood monocyte in HIV patients produced high levels of PGE2 and this could inhibit T-cell proliferative responses. PGE2 production in monocytes, driven by HIV infection in vivo, might in part account for the HIV-related T-cell anergy in these patients and raises the possibility that this may be ameliorated with indomethacin treatment.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Advisers: C McSharry; E Galloway; P Wilkinson
Keywords: Virology
Date of Award: 1993
Depositing User: Enlighten Team
Unique ID: glathesis:1993-72290
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 24 May 2019 15:12
Last Modified: 24 May 2019 15:12
URI: http://theses.gla.ac.uk/id/eprint/72290

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