A new case of blood cell chimerism in pigs

Abstract

Since the first description of blood group chimerism in cattle (Owen, 1945) this subject has been a continual source of interest for studies in domestic animals. The literature describing this rare occurrence in pigs is summarized in Table 1. In the present paper we describe results obtained by examination of blood groups, red cell enzymes, histocompatibility (SLA) antigens and karyotypes in a Landrace pig, which probably establish the first example in pigs of chimerism involving two SLA cell populations.During the blood grouping of samples from pig progeny testing stations, atypical reactions were observed in a sample from a male pig No 241 (2 months of age) by using the Ka, Kc, Kb, Mb and Ee reagents. Subsequently, differential haemolysis proved the presence of two distinct red cell populations. Following treatment of red cells with anti-Ka, 39 % of the cells were left intact, while after treatment with anti-Kb, 61 % of the cells remained unaffected. As can be seen from Table 2, typing of the two cell fractions revealed differences in four blood group systems as well as the Pgd and Ada enzyme systems. Neither of the two cell fractions possessed types identical to those observed in the siblings. A more thorough examination of the siblings using absorption tests which are able to disclose 1 % cell fractions did not show any sign of red cell mixtures. The proportion of the red cell fractions in pig No 241 remained unchanged during the study. According to the standard procedures of progeny testing stations, No 241 was slaughtered at 90 kg ( 5 months of age) and further tests were excluded.SLA typing was performed on lymphocytes from the apparent chimeric pig (No 241), the parents and two littermates. The class I SLA antigens were determined with the panel of SLA antisera described by Kristensen et al. (1985) using the micro-lymphocytotoxicity test. Four distinct SLA haplotypes were demonstrated on the lymphocytes from the chimeric pig, namely FJ 20-8.2.11, FJ 20-7.2, FJ 10.14 235