A Study of the Progenitor Potential and Function of Thymic Nurse Cells Using pH91 a TNC- Specific Monoclonal Antibody
Item
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Title
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A Study of the Progenitor Potential and Function of Thymic Nurse Cells Using pH91 a TNC- Specific Monoclonal Antibody
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Identifier
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d_2009_2013:0930c575165c:10989
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identifier
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11302
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Creator
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Chilukuri, Rajendra V.E.,
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Contributor
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Jerry C. Guyden
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Date
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2011
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Language
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English
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Publisher
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City University of New York.
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Subject
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Cellular biology | Immunology | Cytokeratins | Fork head transcription factor | Monoclonal antibody | Progenitors | Thymic Nurse Cells | Thymus
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Abstract
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Thymic nurse cells (TNCs) are lympho-epithelial complexes that are a major component of the cortical thymic microenvironment. The functional role of TNCs in the thymus has been controversial but recent studies are beginning to elucidate the role of these cells in thymic homeostasis. In the present study, we have described the function of TNCs during the process of thymocyte selection and present results suggestive of the progenitor potential of TNCs.;Using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal microscopic analyses, we show that TNCs create an intimate association with thymocytes. Thymocytes become trapped within unique extra-cytoplasmic spaces generated by the TNCs. The membrane-derived honeycomb-like fenestrae allow visualization of trapped thymocyte movement into and out of these fenestrae, a process that facilitates interactions between the two cell types. Further, we have data confirming an interaction between the alphabetaTCR expressed on trapped thymocytes and MHC class II antigen expressed on the surfaces of the TNCs. We also observe lipid-raft accumulation around the contact point between the thymocytes and TNCs.;When we costained freshly isolated thymic nurse cells with TNC-specific monoclonal antibody pH91 and with K5 and K8 cytokeratin antibodies, we observed a subset of TNC that were K5+K8+ and pH91 +. Previous studies have suggested that k5+k8 + thymic TECs were thymic epithelial progenitor cells. The studies presented here show that TNCs express the transcription factors Foxn1 and p63 both of which play critical role in the thymic determination as well as maintaining a proliferative subpopulation of TECs. Interestingly, when we co-stained embryonic day 11.5 (E11.5) thymic sections with pH91 and Foxn1 antibodies, their expressions were detected in this phase of early thymic organogenesis. The expression of p63 was detected a day later at E12.5. Also, we have results confirming the expression of pH91 antigen as early as E7.5 along with a stem cell marker Oct4.;Finally using confocal analysis and TNC specific mAb, pH91, we show that the classical complex morphology of TNCs first appears at E17.5 stage of development. However, analyses of major histocompatibility complex (MHC) class II expression on embryonic TNCs cell surfaces show its onset from E13.5. The results show a marked increase in the expression of MHC class II, from 36.2% at E13.5 to 69.1% at E18. 5 stage of development.;Taken together, these data suggest that thymic nurse cells play a significant role in the murine thymus; they create membranous spaces that facilitate MHC restriction and express markers implicating them as possessing progenitor ability.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Biology
