Autologous stem cell transplantation for paediatric-onset polyarteritis nodosa: changes in autoimmune phenotype in the context of reduced diversity of the T- and B-cell repertoires, and evidence for reversion from the CD45RO(+) to RA(+) phenotype

We have studied immune reconstitution in a patient with paediatric-onset po lyarteritis nodosa treated with high-dose immuno suppressive agents followe d by stem cell rescue. The patient developed several new autoimmune phenome na over the 18 months after immunosuppression and stem cell rescue. Flow cy tometry, reverse transcription-polymerase chain reaction (RT-PCR) heterodup lex and isotype-specific RT-PCR analysis of immunoglobulin expression showe d that the T- and B-cell repertoires were highly restricted in the first fe w months after treatment. The dominant T-cell clones seen after reconstitut ion were persistently expanded, were different from those which could be de monstrated before autologous stem cell transplantation, and were in the CD8 (+) population. Our data also show that 12 months after treatment these exp anded T-cell clones were within the CD45RA(+) population, suggesting that r eversion from the CD45RO(+) to the CD45RA phenotype had occurred in vivo.