Joint report of the first workshop of the LD typing study group.

In the first workshop of the American LD Typing Study Group, six exchanged typing cells were used by all participants. Several other homozygous typing cells were included in individual experiments by the participating laboratories. The data obtained from LD typing of 142 individuals, among whom were members of 33 families, were submitted for joint analysis by computer. Several typing cells appeared to recognize new HLA-D specificities. Their typing reactions were clearly discernible in the computer analysis of the results using the 25th percentile stabilization method. The next phase of this work will consist of an expanded study of the families included in the present report.