Administration of PLP139-151 primes T cells distinct from those spontaneously responsive in vitro to this antigen

We examined the TCR repertoire used by naive SJL mice in their in vitro spontaneous response to proteolipid protein (PLP) 139-151 by Vbeta-Jbeta spectratyping and compared it to that used after immunization with the peptide. T cells from immunized mice use the public rearrangement Vbeta10-Jbeta1.1, but naive mice do not; in contrast, TCR CDR3-beta rearrangements of Vbeta18-Jbeta1.2 and Vbeta19-Jbeta1.2 consistently are associated with the spontaneous response. T cells involved in spontaneous and induced responses can each recognize PLP(139-151) presented in vivo, but its s.c. administration has different consequences for the two repertoires. Four days after immunization, T cells associated with spontaneous responsiveness appear in the draining lymph nodes but disappear by day 10 and never appear elsewhere. Simultaneously, Vbeta10-Jbeta1.1 T cells are likewise activated in the lymph nodes by day 4 and spread to the spleen by day 10. Eight- to 10-wk-old naive mice use a narrower repertoire of TCRs than do immunized age-matched mice. Induced Vbeta10-Jbeta1.1 T cells home to the CNS during experimental autoimmune encephalomyelitis, whereas we failed to detect Vbeta18-Jbeta1.2 and Vbeta19-Jbeta1.2 TCR rearrangements in the CNS. Thus, we observe that administration of PLP(139-151) primes a T cell repertoire distinct from the one responsible for spontaneous responsiveness. This "immunized" repertoire substitutes for the naive one and becomes dominant at the time of disease onset.