Differences in T15 expression of primary and secondary anti-PC responses with T cells from T15+ and T15- donors.

The expression of T15 idiotype dominance with T cells from T15- mice was investigated. It was found that T15 dominance in the T-dependent response to phosphorylcholine (PC) could be generated by unprimed BALB/c B cells with T cells from T15+ and xid T15- mice. T15 dominance was also expressed when T15 neonatally suppressed BALB/c were used as T cell donors. With PC-primed B cells, however, T15 dominance was not established until 3 wk after adoptive co-transfer with T helper cells from xid NBF1 mice. To further study the different efficiencies of T cells for T15 dominance, limiting dilution analysis was performed. The data demonstrate that T15-specific T cell populations in BALB/c mice and NBF1 male mice differ in their precursor frequencies. In BALB/c mice, a frequent set of T15/M167-recognizing T helper cells is present; a corresponding frequent set of cells is absent in NBF1 males. This difference is likely to be one of the reasons why dominance is not immediately established after transfer of T cells from xid mice.