HLA-D typing by homozygous typing cells. A statistical analysis of experimental and biological variation.

Several normalization procedures have been applied to single MLC-typing experiments in order to neutralize experimental variation and hence to secure assignment of HLA-D phenotypes. The present paper concerns a statistical description and isolation of experimental and biological factors in repeated MLC-typing experiments. The statistical model used gives a meaningful description of the variables in MLC as judged by its application to MLC-typing data of HLA-identical siblings. Subsequent testing of the model in an HLA-A, -B,-C and -D-genotyped family material provides evidence that the level of typing response to selected homozygous typing cells may be influenced by factors coded for by the homologous HLA-D region. It is, however, concluded that such evidence must be accepted with caution due to the (for the present statistical purpose) suboptimal design for the HLA-D typing experiments and hence the relative insensitivity of the method. A general method for locating erroneous triplicates is devised.