Characterization of expanded T cell clones in healthy macaques: ontogeny, distribution and stability

Peripheral expanded T cell clones have been discussed mainly in relation to certain diseases or immune function in humans and mice. There is little in formation on their ontogeny, stability and distribution among T cell subset s as well as major lymphoid organs, We applied reverse transcription-polyme rase chain reaction (RT-PCR) with family specific primers for monkey T cell receptor beta chain V regions and single-strand conformation polymorphism (SSCP) analysis to analyze the expanded T cell clones in cynomolgus monkeys (Macaca fascicularis). A number of expanded T cell clones were detected in the peripheral blood of young and adult monkeys, but few expanded T cell c lones were detected in the blood of a fetus and a 2-day-old neonate. The cl ones in adults were maintained over 3 months. These expanded T cell clones were distributed only in peripheral blood and spleen, but few were found in lymph nodes (axillary, inguinal and intestinal). The number of expanded T cell clones was much greater in CD8 single-positive (CD8sp) T cells than in CD4sp T cells, showing that most of these clones originated in the CD8sp T cell population. Almost all the expanded CD8sp T cell clones belonged to t he CD28(-), CD29(hi) and Fas(+) subset. The usage of V beta genes was not s kewed in the 24 V beta. Furthermore, higher mRNA signals for effector molec ules perforin and IFN-gamma were detected in CD8sp T cell subsets with phen otypes of CD28-, CD29(hi) and Fas(+), suggesting that the expanded T cells might have developed in relation to T cell activation in the periphery of c ynomolgus monkeys. (C) 2000 Elsevier Science Ltd. All rights reserved.