Haptoglobin phenotypes in Brazilian patients with leukemia

Fenótipos da haptoglobina em pacientes brasileiros com leucemia

ORIGINAL PAPER ARTIGO ORIGINAL

Haptoglobin phenotypes in Brazilian patients with leukemia

Fenótipos da haptoglobina em pacientes brasileiros com leucemia

Paulo Vidal Campregher^I; Irene Lorand-Metze^II; Helena Zerlotti Wolf Grotto^III; Maria de Fatima Sonati^III

^IMédico hematologista do Centro de Hematologia de São Paulo; responsável pelo Laboratório de Hematologia da Empresa Diagnósticos da América, São Paulo, SP

^IIProfessora titular de Hematologia do Departamento de Clínica Médica da Faculdade de Ciências Médicas/Hemocentro da Universidade Estadual de Campinas (FCM/UNICAMP)

^IIIProfessora associada da área de hematologia em patologia clínica do Departamento de Patologia Clínica da FCM/UNICAMP

^{Correspondence}

ABSTRACT

Haptoglobin (HP) phenotypes were determined in 188 Brazilian patients with the four most common types of leukemia: acute myeloid leukemia (AML), chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL), and were compared to 197 normal controls. We could not confirm the previously suggested increased incidence of the HP1 gene and the HP1-1 phenotype among leukemic patients. A higher frequency of haptoglobinemics (HP0) was observed among patients, in agreement with previous findings.

Key words: Haptoglobin phenotypes, Leukemia, Genetic polymorphisms, Brazilian population

RESUMO

Os fenótipos de haptoglobina (HP) foram determinados em 188 pacientes brasileiros com os quatro principais tipos de leucemia (LMA, LMC, LLA e LLC) e comparados a 197 controles normais. A existência de associação entre a LMA, a LMC e a LLA e o gene HP-1 e o fenótipo HP 1-1, previamente sugerida na literatura, não foi confirmada no presente estudo. Uma prevalência maior de haptoglobinêmicos (HP0) foi verificada entre os pacientes, em concordância com estudos prévios.

Unitermos: Fenótipos de haptoglobina, Leucemia, Polimorfismos genéticos, População brasileira

Introduction

Haptoglobin (HP) is a hemoglobin binding a₂-globulin fraction of the serum with antioxidant and immunomodulatory properties^{(9, 14, 15, 18, 21, 24)}. In humans, HP is characterized by a genetic polymorphism of the a-chain, with three major phenotypes: HP1-1, HP2-2 and HP2-1, which are the expression of two alleles (HP1 and HP2) on chromosome 16q22.1⁽⁶⁾.

Several authors have evaluated the correlation between HP types and different diseases, such as neoplasias, chronic pathologies, diabetes, hypercholesterolemia, cardiovascular diseases, etc.^{(1-4, 8, 12, 13, 19, 25)}. The significance of this polymorphism in leukemias has also been investigated, with controversial results, suggesting an association of the HP1 gene and the HP1-1 phenotype with AML, CML and ALL^{(7, 16, 17)}. In order to contribute to this matter, we determined the HP phenotypes of 188 Brazilian patients with leukemia.

Material and methods

Serum samples were obtained from 223 adult patients with leukemia, treated either at the UNICAMP University Hospital, in Campinas, or at the São Paulo Hematology Center, in São Paulo, both in the state of São Paulo, Southeast Brazil. Patients were classified into the four main groups: AML (n = 42), CML (n = 78), ALL (n = 20) and CLL (n = 48). Diagnosis and classification were based on the morphologic characteristics of the peripheral blood and bone marrow cells, associated with leukocyte cytochemistry and immunophenotyping⁽⁵⁾. A control group (CG) was composed of 210 blood donors from the same geographical region, 104 Caucasians and 106 African descendants. Thirty-five patients (15.7%) and 13 controls (6.2%) did not present detectable levels of HP, evaluated by electrophoresis on cellulose acetate⁽²³⁾, and were considered ahaptoglobinemic (designated as HP0). They were omitted from the calculation.

HP types were determined by acidic urea polyacrylamide gel electrophoresis⁽²⁰⁾. The patient groups were compared with the controls by using c² test for gene frequency distribution. The Caucasian and African descendant blood donor subgroups were previously compared and did not significantly differ with respect to the HP gene frequencies (p = 0,994) and HP phenotype distribution (p = 0.227), being kept as a unique control group.

Results

The HP phenotypes and HP gene frequencies found in the patients and in the CG are demonstrated in Table 1, while the results of the comparisons between each leukemic group and the controls are summarized in Table 2. We could not find any significant difference in any of these comparisons.

Discussion

Haptoglobin, beside the hemoglobin binding function, is an acute-phase reactant protein; its antioxidant and immunomodulatory properties have been extensively investigated^{(14, 15, 18, 24)}. It has recently been demonstrated that different HP phenotypes show distinct antioxidant activities and that the HP 2-2 phenotype is a less effective protector than HP1-1^{(1, 14)}. The latter corresponds to a small and dimeric protein, while 2-1 is a linear polymer with intermediate dimension and 2-2 is a large cyclic polymer. These characteristics are important determinants of the biological activities of each HP subtype⁽¹⁴⁾. In diabetes, for instance, HP has been focused as one major genetic factor involved in the susceptibility to coronary artery disease⁽¹²⁾. In cancer, this correlation is not so clear. Awadallah and Atoum, investigating patients with breast cancer, found that the family history plays a relevant role in determining the degree of association between the disease and HP polymorphism⁽²⁾. In leukemias, a recent study using microarray technology to analyze gene expression in CML cells demonstrated that the HP gene is one of the up-regulated genes⁽¹⁰⁾. The authors, however, did not compare different HP genotypes. So, their influence on the mechanisms of defense or susceptibility to disease remains inconclusive, meaning that far more studies are necessary to clear up the relation of HP subtypes and leukemias.

Conclusion

The previously reported high incidence of the HP1 gene and the HP1-1 phenotype among patients with AML, CML and ALL^{(7, 16, 17)} could not be confirmed in this study, since no significant differences were found in the comparisons. On the contrary, here the patients with CLL showed the highest incidence of the HP2 gene (0.604), with a p value tending towards significance (p = 0.061).

The previously reported high incidence of undetectable HP in leukemia patients⁽¹⁷⁾ was confirmed in this study (p = 0,002). The HP0 phenotype may be primarily due either to deletions that remove the HP genes or to point mutations that inactivate them^{(11, 22)}. These data must be carefully evaluated, however, because patients with leukemia often have associated conditions that can reduce the plasmatic HP levels, such as hemolysis or hepatic disease.

Acknowledgments

We thank Ms. E.M. Kimura and A.S. Gervasio for technical assistance, Professor Celso Guerra, of the São Paulo Hematology Center, for kindly providing us part of the sera samples, and the Statistics Committee of the School of Medical Sciences/UNICAMP, for the comparative analyses. Funding from FAPESP/Brazil.

Primeira submissão em 10/02/04

Última submissão em 30/04/04

Aceito para publicação em 03/05/04

Publicado em 20/10/04

Trabalho desenvolvido no Departamento de Patologia Clínica da FCM/UNICAMP, com amostras de pacientes provenientes das enfermarias e ambulatórios de hematologia clínica da disciplina de Hematologia e Hemoterapia do Departamento de Clínica Médica da FCM/UNICAMP. Suporte financeiro: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP).

• 1. AWADALLAH, S. M. Haptoglobin 2-2 phenotype is associated with decreased ferroxidase activity in smokers. Clin Chim Acta, v. 334, p. 71-6, 2003.
• 2. AWADALLAH, S. M.; ATOUM, M. F. Haptoglobin polymorphism in breast cancer patients from Jordan. Clin Chim Acta, v. 341, p. 17-21, 2004.
• 3. BECKMAN, G. et al. Haptoglobin groups and lung cancer. Hum Hered, v. 36, p. 258-60, 1986.
• 4. CHANDRA, T. et al. Haptoglobin phenotypes in diabetes mellitus and diabetic retinopathy. Hum Hered, v. 41, p. 347-50, 1991.
• 5. DACIE, J. V.; LEWIS, S. M. Practical Haematology 9^th edition. London: Churchill Livingstone, 2001.
• 6. DELANGHE J. et al. Haptoglobin 1F allele frequency is high among indigenous populations in the State of Durango, Mexico. Hum Hered, v. 50, p. 263-5, 2000.
• 7. FRÖHLANDER, N. Haptoglobin groups and leukemia. Hum Hered, v. 34, p. 311-3, 1984.
• 8. FRÖHLANDER, N.; STENDAHL, U. Haptoglobin groups in ovarian carcinoma. Hum Hered, v. 38, p. 180-2, 1988.
• 9. GUTTERIDGE, J. M. The antioxidant activity of haptoglobin towards hemoglobin-stimulated lipid peroxidation. Biochim Biophys Acta, v. 917, p. 219-23, 1987.
• 10. KANETA, Y. et al. Genome-wide analysis of gene-expression profiles in chronic myeloid leukemia cells using a cDNA microarray. Int J Oncol, v. 23, p. 681-91.
• 11. KODA, Y. et al. Simple PCR detection of haptoglobin gene deletion in anhaptoglobinemic patients with antihaptoglobin antibody that causes anaphylatic transfusion reactions. Blood, v. 95, p. 1138-43, 2000.
• 12. LEVY, A. P. Genetics of diabetic cardiovascular disease: identification of a major susceptibility gene. Acta Diabetol, v. 40, suppl. 2, S330-3, 2003.
• 13. LEVY, A. P. et al. Haptoglobin phenotypes and vascular complication in diabetes. N Engl J Med, v. 343, p. 369-70, 2000.
• 14. MELAMED-FRANK, M. et al. Structure-function analysis of the antioxidant properties of haptoglobin. Blood, v. 98, p. 3693-8, 2001.
• 15. MILLER, Y. I. et al. Oxidation of low-density lipoprotein by hemoglobin stems from a heme-initiated globin radical. Antioxidant role of haptoglobin. Biochemistry, v. 36, p. 12189-98, 1997.
• 16. MITCHELL, R. J. et al. Associations between the two serum proteins haptoglobin and transferrin and leukemia. Hum Hered, v. 38, p. 144-50, 1988.
• 17. NEVO, S.; TATARSKY, I. Serum haptoglobin types and leukemia. Hum Hered, v. 73, p. 240-4, 1986.
• 18. OH, S. K. et al. Specific binding of haptoglobin to human neutrophils and its functional consequences. J Leuk Biol, v. 47, p. 142-8, 1990.
• 19. ROGUIN, A. et al. Haptoglobin phenotype and the risk of restenosis after coronary artery stent implantation. Am J Cardiol, v. 89, p. 806-10, 2002.
• 20. SANTORO, C. et al. A simplified procedure for haptoglobin subtyping. Hum Genet, v. 60, p. 287-8, 1982.
• 21. SMITH, A. B.; HAJDUK, S. L. Identification of haptoglobin as a natural inhibitor of trypanocidal activity in human serum. Proc Natl Acad Sci USA, v. 92, p. 10262-6, 1995.
• 22. TEYE, K. et al. A novel I247T missense mutation in the haptoglobin 2 beta-chain decreases the expression of the protein and is associated with ahaptoglobinemia. Hum Genet, v. 114, p. 499-502, 2004.
• 23. VALERI, C. R. et al. Quantitation of serum hemoglobing-binding capacity using cellulose acetate membrane electrophoresis. Clin Chem, v. 11, p. 581-8, 1965.
• 24. WANG, Y. et al. Haptoglobin, an inflammation-inducible plasma protein. Redox Rep, v. 6, p. 379-85, 2001.
• 25. ZHAO, H.; ZHANG, G. Haptoglobin groups and cirrhosis of the liver. Hum Hered, v. 43, p. 134-6, 1993.

Publication Dates

• Publication in this collection
  16 Nov 2004
• Date of issue
  Oct 2004

History

• Received
  10 Feb 2004
• Reviewed
  30 Apr 2004
• Accepted
  03 May 2004