Pulmonary Langerhans cell histiocytosis "de novo" after lung transplantation.

A pulmonary Langerhans cell histiocytosis is presented in a 40 year-old woman two years after bilateral lung transplantation for emphysema without any signs of Langerhans cells proliferation in the explanted lungs. A microsatellite molecular analysis showed the proliferating cells were generated in a recipient cellular clone. The patient did not quit smoking after transplantation. No signs of disease were detected in the implanted lungs before surgery. Strict control of immunosupressive drug levels stabilized the disease. A "de novo" monoclonal origin of stem cells, probably from the bone marrow is suggested. The reason she did not develop disease in the native lungs is unknown, although we suggest an interaction between tobacco or some other antigens and local cellular receptors.

Chimerism analysis in transplant patients: a hypothesis-free approach in the absence of reference genotypes.

INTRODUCTION: During routine analysis of chimerism in bone marrow transplant patients pre-transplant genotype of the recipient or the donor might lack. We aimed to develop a new method to analyze DNA results suitable when reference genotypes are not available. METHODS: The method was based on the balance between heterozygotes. It was implemented in a standard computer spreadsheet, and considered the hypothetical donor-recipient genotype combinations. Hypotheses with peak height ratios and allele sharing tendency above a critical threshold were accepted. The results were compared with those obtained with prior knowledge of reference genotypes. RESULTS: The algorithm predicted correctly the proportion of donor/recipient chimerism, even in the absence of reference genotypes. In fact, the predicted values were closely correlated (r(2)>0.98) and free of systematic bias (slope 0.98-1.04), in comparison with the reference values obtained with prior knowledge of the donor and recipient genetic profiles. CONCLUSIONS: This study constitutes a proof-of-concept of the application of the heterozygote balance for the quantitative study of chimerism. The algorithm computes post-transplant chimerism in an easy and time-efficient way, even when the donor and recipient reference genotypes are unavailable. Therefore, it can be a useful tool for laboratories involved in chimerism analysis.