Prevalence of chimerism after non-myeloablative hematopoietic stem cell transplantation / Prevalência do quimerismo após transplante de células hematopoiéticas não-mieloablativo

Context and objective: Non-myeloablative hematopoietic stem cell transplantation (NMA-HSCT) is performed in onco-hematological patients who cannot tolerate ablative conditioning because of older age or comorbidities. This approach does not completely eliminate host cells and initially results in mixed chimerism. Long-term persistence of mixed chimerism results in graft rejection and relapse. Involvement of graft-versus-host disease is concomitant with complete chimerism and graft-versus-tumor effect. The aim of this study was to evaluate the prevalence of chimerism in onco-hematological patients who underwent NMA-HSCT. Desingn and setting: Observational clinical study on chimerism status after human leukocyte antigen-identical NMA-HSCT at the Discipline of Hematology and Hemotherapy of Universidade Federal de São Paulo. Methods: We sequentially analyzed the amplification of APO-B, D1S80, DxS52, FVW, 33.6, YNZ-2 and H-ras primers using variable number of tandem repeats (VNTR) on 17 pairs and fluorescent in situ hybridization (FISH) with the XY probe and SRY primer on 13 sex-unmatched pairs. RESULTS: The informativeness of the primers using VNTR was 60 percent for APO-B, 75 percent D1S80, 36 percent DxS52, 14 percent FVW, 40 percent YNZ-22 and 16 percent H-ras. The SRY primer was informative in female receptors with male donors. The XY-FISH method was informative in 100 percent of the sex-unmatched pairs. Conclusion: These methods were sensitive and informative. In VNTR, the association of APO-B with D1S80 showed 88 percent informativeness. The quantitative FISH method was more sensitive, but had the disadvantage of only being used for sex-unmatched pairs.

Contexto e objetivo: O transplante de células hematopoiéticas não-mieloablativo é realizado em pacientes com doenças onco-hematológicas que não suportam condicionamentos ablativos devido à elevada idade ou ao acometimento por comorbidades. Esta abordagem não elimina completamente as células do hospedeiro, resultando, inicialmente, em quimerismo misto. A persistência do quimerismo misto na evolução de longo prazo resulta na rejeição ao enxerto e recaída. O acometimento pela doença do enxerto contra hospedeiro é concomitante ao quimerismo completo e ao efeito enxerto versus tumor. O objetivo deste estudo foi avaliar a prevalência do quimerismo em doenças onco-hematológicas tratadas com o transplante não-mieloablativo de células hematopoiéticas. Tipo de estudo e local: Estudo clínico observacional do estado de quimerismo após transplante antígenos leucocitários humanos-idêntico não-mieloabaltivo realizado na Disciplina de Hematologia e Hemoterapia da Universidade Federal de São Paulo. Métodos: Analisamos sequencialmente a amplificação dos primers APO-B, D1S80, DxS52, FVW, 33,6, YNZ-22, H-ras pelo VNTR (variable number of tandem repeats) em 17 pares e FISH (fluorescent in situ hybridization) pela sonda XY e do primer SRY em 13 pares de não relacionados a sexo. Resultado: A informatividade dos primers pelo VNTR foi de 60 por cento para APO-B; 75 por cento D1S80; 36 por cento DxS52; 14 por cento FVW; 40 por cento YNZ-22 e 16 por cento H-ras. O primer SRY foi informativo em receptores femininos com doadores masculinos. O método XY-FISH foi informativo em 100 por cento dos pares de não relacionado a sexo. Conclusão: Estes métodos foram sensíveis e informativos. No VNTR, a associação do APO-B com D1S80 mostrou 88 por cento de informatividade. O FISH, método quantitativo, foi mais sensível, porém com desvantagem de ser usado somente nos pares não relacionados a sexo.

Prevalence of chimerism after non-myeloablative hematopoietic stem cell transplantation.

CONTEXT AND OBJECTIVE: Non-myeloablative hematopoietic stem cell transplantation (NMA-HSCT) is performed in onco-hematological patients who cannot tolerate ablative conditioning because of older age or comorbidities. This approach does not completely eliminate host cells and initially results in mixed chimerism. Long-term persistence of mixed chimerism results in graft rejection and relapse. Involvement of graft-versus-host disease is concomitant with complete chimerism and graft-versus-tumor effect. The aim of this study was to evaluate the prevalence of chimerism in onco-hematological patients who underwent NMA-HSCT. DESIGN AND SETTING: Observational clinical study on chimerism status after human leukocyte antigen-identical NMA-HSCT at the Discipline of Hematology and Hemotherapy of Universidade Federal de São Paulo. METHODS: We sequentially analyzed the amplification of APO-B, D1S80, DxS52, FVW, 33.6, YNZ-2 and H-ras primers using variable number of tandem repeats (VNTR) on 17 pairs and fluorescent in situ hybridization (FISH) with the XY probe and SRY primer on 13 sex-unmatched pairs. RESULTS: The informativeness of the primers using VNTR was 60% for APO-B, 75% D1S80, 36% DxS52, 14% FVW, 40% YNZ-22 and 16% H-ras. The SRY primer was informative in female receptors with male donors. The XY-FISH method was informative in 100% of the sex-unmatched pairs. CONCLUSION: These methods were sensitive and informative. In VNTR, the association of APO-B with D1S80 showed 88% informativeness. The quantitative FISH method was more sensitive, but had the disadvantage of only being used for sex-unmatched pairs.