Phenotypic analysis of the medullary-type CD4-CD8+ thymocytes in mice

Phenotypic analysis of the medullary-type CD4 CD8+ (CD8SP) thymocytes has revealed phenotypic heterogeneity within this cell population. The phenotype of mature peripheral CDS+T cells is TCRαβ+CD3+Qa-2+HSA 3G11 6C10, whereas in the medullary-type CD8SP thymocytes, 20% are Qa-2+; 33%, HAS; 30%, 3G11; and 70% are 6C10. The disparate expression patterns of these four cell surface markers suggest that medullary-type CD8SP thymocytes may undergo phenotypic maturation process. According to the distribution of these four cell surface markers, six subgroups of CD8SP thymocytes have been identified. The precursor-progeny relationship along with developmental pathway is postulated as follows: 6C10+HSA+3G11 Qa-2→ 6C10+HSA+ 3G11+Qa-2 → 6C10 HSA+3G11+Qa-2 → 6C10 HSA 3G11+Qa-2 → 6C10 HSA 3G11 Qa-2 → 6C10 HA S 3G11 Qa-2+, the cells in the last subgroup exit the thymus and home into periphery.