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The Pgp-1 antigen is expressed on early fetal thymocytes
Insights
Bone marrow prothymocytes and fetal thymocytes express the Pgp-1 glycoprotein. This suggests that Pgp-1 positive (Pgp-1+) cells represent early thymocyte progenitors during development.
Area of Science:
- Immunology
- Developmental Biology
- Cell Biology
Background:
- The Pgp-1 glycoprotein is found on bone marrow prothymocytes and specific intrathymic progenitor cells in adult animals.
- In adult animals, only a small fraction (approximately 5%) of thymocytes strongly express Pgp-1.
Purpose of the Study:
- To investigate the expression pattern of Pgp-1 during fetal thymocyte development.
- To determine if Pgp-1 expression correlates with early thymocyte progenitor populations.
Main Methods:
- Flow cytometric analysis of fetal thymocytes at different gestational days.
- Two-color immunofluorescence staining to assess co-expression of Pgp-1 and Thy-1.
Main Results:
- Fetal thymocytes (day 13-14 gestation) show high Pgp-1 expression (80-90%), with most cells being Thy-1 negative.
- By days 15-16 of gestation, Pgp-1+ cell percentage decreases as Thy-1 expression becomes dominant.
- Co-expression of Pgp-1 and Thy-1 is observed in a subset of cells.
- Pgp-1+ cell numbers decline further, reaching adult levels by day 19.
Conclusions:
- The dynamic changes in Pgp-1 expression during fetal development indicate its role in early thymocyte progenitor populations.
- Observations support the hypothesis that Pgp-1 marks at least some classes of thymocyte progenitor cells.
Abstract:
The Pgp-1 glycoprotein is expressed on the bone marrow prothymocyte and on a class of intrathymic progenitor cells in the adult animal. Only 5% of adult thymocytes are strongly Pgp-1+. When fetal thymocytes of day 13-14 of gestation are examined by flow cytometric analysis, 80-90% of thymocytes are Pgp-1+, while the bulk of thymocytes are Thy-1-. By day 15-16, the percentage of Pgp-1+ cells begins to fall while nearly all cells become Thy-1+. Two-color immunofluorescence indicates that many Pgp-1+ cells are Thy-1+. The percentage of Pgp-1+ cells continues to fall over the next several days, reaching adult levels by day 19. These observations are consistent with the interpretation that at least some classes of thymocyte progenitors are Pgp-1+.