Mixed Lymphocyte Reactivity in Chimpanzees. I. Some Technical and Genetic Aspects*

Abstract

One-way mixed lymphocyte culture (MLC) tests were performed among the members of 5 chimpanzee harems in all the following possible combinations: parents, parent-child, siblings and half-siblings. The technical aspects of MLC testing in chimpanzees appeared to be very similar to those observed for human and rhesus mondey MLC. The following unexpected observations were made for which no satisfactory explanation can as yet be given. The occurrence of animals with consistently high autologous values and the existence of chimpanzees displaying low MLC responsiveness. The high autologous values occurred mostly in older imported animals (25% with high autologous values only one of the 45 laboratory born animals showed this phenomenon. Low responsiveness occurred in a few offspring belonging to a single harem only and is therefore likely to be genetically controlled but, as it appeared, not by genes linked to ChLA. Data suggesting the existence of MHC[major histocompatability complex]-linked major MLC or D locus were confirmed and extended. A gene dose effect for D locus antigens was demonstrable, i.e., combinations of related animals differing for 1 showed lower MLC responses than combinations differing for 2 ChLA haplotypes. The number of D locus alleles was estimated to be 10.