highly significantP < 0.003
SB1 6 19 6 38 SB4 12 39 11 69 SB5 1 3 4 25 DRI~ 5 16 2 13 DR2 11 35 6 38 DR3 14 45 7 44 DR4 7 23 2 13 DR5 7 23 0 0 DR7 5 16 6 38 DR blank 1 3 0 0 * Binding of ILR 1 to LCL was ascertained by FMF. The statistical significance (by chi square analysis) of the overall correlation between ILR1 and SB is highly significant (P < 0.003) but of the overall correlation between ILR1 and the six well-defined DR alleles is not signifi- cant (P = 0.33). 734 SEROLOGIC DEFINITION OF SECONDARY B CELL ANTIGENS with the interpretation that ILR1 binds to all DR5, SB2, and SB3 molecules.