Constant IFNgamma mRNA to protein ratios in cord and adult blood T cells suggests regulation of IFNgamma expression in cord blood T cells occurs at the transcriptional level.
Low levels of IFNgamma produced by umbilical cord blood (UCB) T lymphocytes upon activation may be due to the need for a high threshold of activation or to intrinsic blocking transcription/translation. We examined IFNgamma mRNA accumulation and protein expression in pharmacologically stimulated human UCB and adult blood (AB) T cells. Our data indicate that both IFNgamma mRNA accumulation and protein synthesis were significantly lower in stimulated UCB T cells than the AB T cells. Since the RNA dependent kinase PKR, an inhibitor of translation, can be activated by low levels of IFNgamma mRNA, we measured its involvement. Treatment with 2-amino-purine, an inhibitor of PKR, did not enhance IFNgamma protein expression in UCB T cells. Furthermore, our studies indicated that IFNgamma promoter hypermethylation does not appear to regulate IFNgamma expression either, as treatment with the demethylating agent, 5-aza-2'-deoxycytidine, did not lead to a significant increase in IFNgamma mRNA accumulation in UCB T cells. What is readily evident from our studies is that the IFNgamma mRNA to protein ratio was similar in UCB and AB T cells and it was not altered by any of the treatments used. These results therefore suggests that IFNgamma expression in UCB T cells is suppressed at the transcriptional level by an unknown mechanism(s).
Gupta
A Kumar
AK
Laboratory for Prenatal Medicine, University Women's Hospital/Department of Research, University of Basel, Spitalstrasse, 21 CH 4031 Basel, Switzerland.
Rusterholz
C
C
Holzgreve
W
W
Hahn
S
S
D015075:2-Aminopurine / Q000494:pharmacology; D000328:Adult; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005312:Fetal Blood / Q000276:immunology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D008213:Lymphocyte Activation / Q000276:immunology; D011401:Promoter Regions, Genetic / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014158:Transcription, Genetic / Q000276:immunology*; D019892:eIF-2 Kinase / Q000037:antagonists & inhibitors / Q000276:immunology
D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D015075:2-Aminopurine; D007371:Interferon-gamma; D019892:eIF-2 Kinase