Abundance of naturally expressed B6dom1 and H-Y epitopes. Synthetic B6dom1 and H-Y peptides, as well as cell extracts, were fractionated by RP-HPLC. Both synthetic and natural B6dom1 peptides were recovered in HPLC fraction no. 18, while synthetic and natural H-Y peptides were recovered in fraction no. 27. (A) The activity of natural H-Y peptide extracted from 1.6 × 107 C57BL/6 male cells is plotted on a dose response curve showing the activity of graded concentrations of synthetic H-Y peptide mixed with competitor peptides extracted from 1.6 × 107C57BL/6 female cells. Also evaluated were the activity of 4 × 106, 8 × 106, and 1.2 × 107cell extracts from C57BL/6 male cells giving 3, 7, and 12 copies per cell, respectively (data not shown). One representative experiment of three is shown. (B) The activity of natural B6dom1 peptide extracted from 4 × 106 C57BL/6 male cells or 1.6 × 107 129 male cells is plotted on dose response curves depicting the activity of graded concentrations of synthetic B6dom1 peptide mixed with competitor peptides extracted from 4 × 106 (▪) or 1.6 × 107 (○) C3H.SW male cells, respectively. Also evaluated were the activities of extracts from 8 × 106, 1.2 × 107, or 1.6 × 107 C57BL/6 male cells and 4 × 106, 8 × 106, or 1.2 × 107 129 male cells. The number of epitope copies per cell was established at 824, 903, and 1,200, respectively for C57BL/6, and at 112, 126, and 107 copies for 129 cells (data not shown). One representative experiment of three is shown. (C) The activity of natural B6dom1 peptide extracted from 8 × 106 (C57BL/6J × C3H.HeJ)F1cells is plotted on a dose response curve depicting the activity of graded concentrations of synthetic B6dom1 peptide mixed with competitor peptides extracted from 8 × 106 C3H.SW male cells, respectively. One representative experiment of two is shown. Targets were T2Db cells. E:T ratio was 5:1 for anti-B6dom1 effectors (SW10/B cell line) and 50:1 for anti–H-Y effectors.
