RESISTANCE AND SUSCEPTIBILITY TO CYCLOSPORINE-A AS CD3(-)4(-)8(-) HUMAN THYMOCYTES DIFFERENTIATE IN-VITRO

Citation
Lm. Pilarski et al., RESISTANCE AND SUSCEPTIBILITY TO CYCLOSPORINE-A AS CD3(-)4(-)8(-) HUMAN THYMOCYTES DIFFERENTIATE IN-VITRO, Scandinavian journal of immunology, 39(4), 1994, pp. 363-372
Citations number
62
Categorie Soggetti
Immunology
ISSN journal
03009475
Volume
39
Issue
4
Year of publication
1994
Pages
363 - 372
Database
ISI
SICI code
0300-9475(1994)39:4<363:RASTCA>2.0.ZU;2-N
Abstract
Human T-cell development appears to be relatively resistant to cyclosp orin A (CsA). Children exposed to CsA in utero as part of kidney trans plant maintenance have few abnormalities. The objective of the study d escribed here was to analyse the effects of CsA on the development in vitro of human multinegative (MN) (CD3(-)4(-)8(-)) thymocytes as a mod el system for thymic progenitor development in vivo. MN thymocytes, pr epared by depletion methods, differentiated in vitro to acquire CD3 an d undergo transitions in CD45 isoform expression analogous to those po stulated to occur in vivo. In this work MN thymocytes were cultured wi th IL-2 and on thymic epithelial cells (TEC) with or without IL-2, eit her in the presence or absence of CsA. For many thymocyte preparations , differentiation in the presence of CsA resulted in almost complete i nhibition of the acquisition of CD3 and of the low Mr isoform CD45R0. Expression of CD45RA and of total CD45 were reduced but not eliminated and the density of CD29 was unaffected. For others, neither CD3 nor C D45 expression was affected, but selective inhibition of TCR delta exp ression occurred. At all doses of CsA (0.1-100 mu g/ml), MN thymocytes continued to cycle indicating a CsA-resistant generative compartment. Treatment of peripheral blood T cells with CsA had no effect on surfa ce expression of CD3 or CD45 isoforms but did reduce the amount of de novo-synthesized CD45R0 mRNA. Culture of MN thymocytes on TEC rendered them virtually resistant to the negative effects of CsA. CD3 acquisit ion was unhindered and total CD45 remained high, but the transition fr om CD45RA to CD45R0 appeared to be delayed. In the absence of TEC, exp ression of both TCR alpha beta and of TCR delta was inhibited, but on TEC, TCR delta was actually up-regulated in some conditions. The effec ts of CsA on human thymocyte development appeared to be modulated by t he physiological state of the donor and the growth conditions to which the cells were subjected. Conditions which most closely approximated those manifest in vivo rendered thymocytes most resistant to the negat ive effects of CsA. The amount of CsA required to affect differentiati on in vitro was significantly higher than could be attained in vivo su ggesting that the immunomodulatory effects of CsA in the maintenance o f organ transplants may derive from an as yet uncharacterized mechanis m.