J Immunol. 1995 Oct 15;155(8):3806-14. Unique Identifier : AIDSLINE
Minor thymus subpopulations representing possible intermediates in
thymic positive selection were isolated by cell sorting from bcl-2
transgenic mice, and cultured 1 to 4 days in simple medium to assess
their ability to spontaneously develop the surface phenotype of mature T
cells. Recovery of cells was in the 60 to 80% range, and no cell
proliferation occurred. Only cells originally expressing high, near
mature T cell levels of CD3 developed further in culture by
down-regulation of CD4 or CD8. The main mature cell product was CD4-8+,
regardless of whether the starting phenotype of the CD3high
intermediates was CD4+8+, CD4int8+, or CD4+8int; only an intermediate
subpopulation expressing the highest levels of CD4 (CD4high8int)
produced a dominance of CD4+8- mature progeny. Partial down-regulation
of CD8 was therefore not a good indicator of CD4+ T lineage commitment.
These and previous results indicate that maturation to the CD8+ T
lineage involves a rapid up-regulation of the TCR-CD3 complex, but a
relatively slow down-regulation of CD4; it may also involve a partial,
transient reduction in surface CD8. In contrast, maturation to the CD4+
T lineage involves a relatively rapid down-regulation of CD8, with
maintenance of high levels of CD4. There appears to be a marked
asymmetry in the developmental steps leading from CD4+8+ thymocytes to
the CD8+ or to the CD4+ T cell lineage.
Animal Cell Differentiation CD4-CD8 Ratio CD4-Positive
T-Lymphocytes/*IMMUNOLOGY CD8-Positive T-Lymphocytes/*IMMUNOLOGY
Lymphocyte Transformation Mice Mice, Inbred C57BL Mice, Transgenic
Proto-Oncogene Proteins/GENETICS Receptor-CD3 Complex, Antigen,
T-Cell/*METABOLISM Support, Non-U.S. Gov't T-Lymphocyte
Subsets/*IMMUNOLOGY Thymus Gland/CYTOLOGY Up-Regulation
(Physiology)/*IMMUNOLOGY JOURNAL ARTICLE