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-gene repertoires both by fluorescence-activated cell sorter (FACS) analysis with the avialable TCR V region-specific mAbs and by the polymerase chain reaction (PRC) with TRC V gene family-specific oligonucleotides. Among the low number of CD3+ T cells, most of the TRC V region tested for could be detected by FACS analysis in liver, bone marrow, and spleen derived from a 14-week-old fetus and two 15-weeks-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 was found in liver and bone marrow. This was most probably the consequence of the low number of CD3⁺ T cells in these organs. In 17-week-old week-old fetal thymi the level of expression of some TCRAV and TCRBV gene families, in particular those that contain single member, was lower compared to post-partum thymi and adult peripheral blood mononuclear cells. The combined data of FACS and PCR analysis demonstrate that TCR genes belonging to the majority of TCR V gene families can be used in TCR α and β chain rearrngements during early human fetal life. Our data also suggest that the expression levels of some of the single member TCR V gene families may be influenced by the development stage.