Use of polymorphic DNA probes to test the lymph nodes of infants and fetuses for spontaneous chimerism

Spontaneous chimerism is rare, but it has been observed in infants who have received intrauterine transfusions, or in those infants who have severe combined immunodeficiency disease. The site of maternal cell engraftment has not been identified in these cases, but it is apparently not the bone marrow. Lymph nodes have not been investigated. Based on recent experimental data that showed that foreign cells grow in the lymph nodes, but not in the marrows of perinatally inoculated mice, the decision was made to use highly specific polymorphic DNA probes to assay for the presence of maternal DNA in the nodes that were removed from three infants and two fetuses. No evidence for the engraftment of maternal cells was detected at a 5% level of sensitivity. These results were in accord with findings from previous work that has shown that the placenta and host-resistance mechanisms combine to make spontaneous chimerism a rare event. The results also showed that similar tests for maternal cell engraftment in lymph nodes and other sites, not previously evaluated, are feasible and perhaps indicated in infants with congenital and acquired immunodeficiencies, such as severe combined immunodeficiency disease and acquired immunodeficiency syndrome.