USAGE OF TCRAV AND TCRBV GENE FAMILIES IN HUMAN FETAL AND ADULT TCR REARRANGEMENTS

We have investigated fetal and adult T-cell receptor (TCR) A and B V-g ene repertoires both by fluorescence-activated cell sorter (FACS) anal ysis with the available TCR V region-specific mAbs and by the polymera se chain reaction (PCR) with TCR V gene family-specific oligonucleotid es. Among the low number of CD3+ T cells, most of the TCR V regions te sted for could be detected by FACS analysis in liver, bone marrow, and spleen derived from a 14-week-old fetus and two 15-week-old fetuses. Similarly, the PCR analysis showed that the majority of the TCRAV and TCRBV families were expressed in the peripheral organs of the 13-week- old fetus, although an apparent absence of particular TCR V families w as found in liver and bone marrow. This was most probably the conseque nce of the low number of CD3+ T cells in these organs. In 17-week-old fetal thymi the level of expression of some TCRAV and TCRBV gene famil ies, in particular those that contain a single member, was lower compa red to post-partum thymi and adult peripheral blood mononuclear cells. The combined data of FACS and PCR analysis demonstrate that TCR V gen es belonging to the majority of TCR V gene families can be used in TCR alpha and beta chain rearrangements during early human fetal life. Ou r data also suggest that the expression levels of some of the single m ember TCR V gene families may be influenced by the developmental stage .