Clinical and laboratory characterization of adult T-cell leukemia/lymphoma in patients from Salvador, Bahia

The adult T-cell leukaemia / lymphoma (ATLL) is a serious haematological disease associated with Human Type 1 T-cell Lymphotropic Virus infection (HTLV-1)1. The HTLV-1 has the ability to transform and immortalize T cells, however, only about 5% of infected individuals develop ATLL, usually manifesting clinical symptoms after a prolonged period of viral latency2 3 4.

This disease has an unpleasant prognosis, rapid clinical evolution and diverse manifestations, and is commonly characterized by short survival time and poor response to chemotherapy, important points that are distinguished from other types of leukemias5. Differentiation between anomalous and normal cells is based on phenotypic patterns that are distinct in these cell populations6. Therefore, most patients that develop ATLL exhibit the phenotype mature CD4 + T cell and express some surface markers, partial loss or complete absence of others7 8.

It is estimated that approximately 20 million of people worldwide are infected for this retrovirus that ATLL causer and in Brazil there are several regions that are classified as endemic for this virus1. In the north and northeast of Brazil there are high percentages of seroprevalence for HTLV-1 and Bahia occupies second position in the national ranking with 0.0094% of cases9 10.

This is a descriptive, retrospective, time series study, obtained from the database available at the diagnostic service of the Laboratório de Imunologia e biologia molecular of the Instituto de Ciências da Saúde (ICS) of the Universidade Federal da Bahia (UFBA) from 2010 to 2018. The data were treated from the analysis of reports performed by the technique of flow cytometry immunophenotyping, available by the lab.

Based on the data from the reports, the search for electronic clinical records was initiated through the Sistema de Monitoramento e Avaliação dos Resultados do Programa Nacional Telessaúde Brasil Redes (SMART), made available by Complexo Hospitalar Universitário Professor Edgard Santos (Com-HUPES) for additional data.

This study, information was collected and the evaluated data were: demographic variables (sex; age of diagnosis, biochemical profile, clinical form, proportional distribution of morbidity and treatment used); biochemical profile (calcium, creatinine, lactate dehydrogenase - LDH, magnesium, potassium, sodium, urea); clinical form; HTLV-1 serology; clinical form of ATLL; leukogram; immunophenotyping (used markers - CD45; CD2; CD3; CD4; CD5; CD7; CD25; CD8).

Seropositivity for HTLV-1 was verified for all clinical records of patients, diagnosis was based on serological evidence of HTLV-1by enzyme-linked immunosorbent assay and confirmed by western blot test, all patients included in the study had positive serology for this two test. The clinical form of each patient was classified according to the Shimoyama criteria and the addition of Bittencourt's PCT form suggestion11.

The immunogenotyping made available in the reports was performed with monoclonal antibodies conjugated with different fluorochromes, the reagents used were validated by the laboratory as determined by RDC 302/ 2005 - ANVISA. The anomalous cells were acquired by flow cytometry (CMF) through the FACSCalibur-BD and FACSCanto II - BD cytometers and the Infinicyt ™ Cytognos® Software was used to identify cell populations.The data CMF were classified by antigenic expression intensity in the analyzed cells, this classified they are in the clinical reports, according demonstrated totable 1.

In this work, the statistical methodology was applied for descriptive frequency epidemiology analysis from obtained data, where the average frequencies, medians, as well as the respective confidence intervals were calculated by the program.

The statistical tests Non-parametric Wilcoxon and Mann-Whitney were also applied for the association between the variables presented by the patients. The overall survival were calculated by the KaplanMeier method and compared by the log-rank test. For statistical purposes, a value of p <0.05 was considered as a significant probability.

This work was accomplished in accordance with the terms of resolution 466/12 of Conselho Nacional de Saúde. Submitted and approved by Comitê de Ética e Pesquisa (CEP) - ICS, through the Plataforma Brasil and with technical advice/ resolution number 10205918.6.0000.5662.

According to the findings of Arisawa et al. (2000) and Carneiro-Proietti et al. (2002) the first signs of clinical manifestations of ATLL begin with older age, with the apex of its pathological expression between 40 - 60 years of age, which was consistent with the age range observed in the studied population. The development and expression of this hematological disease after the fourth decade of life is a result of the viral incubation time, as well as the weak induction of the immune system during this long latency period, thus enabling the clonal expansion of the affected cells, as well as accumulation of mutations and cellular transformation14.

In 2006, Mota et al. highlighted that the low socioeconomic power, older individuals and females are some risk factors for the pathological development of HTLV-1 and these characteristics are similar to the profile of the population evaluated. Thus, the present study suggests that women have a slight tendency to develop ATLL, just as they have clinical manifestations a few years earlier than men.

In the present study, the women was more often for acute clinical manifestation and smoldering. The acute condition is reported as one of the most aggressive categories of ATLL and the smoldering condition, also called indolent is referred to as an intermediate stage between an patient asymptomatic HTLV-1 or with monoclonality, as this condition may have no symptoms for many years13 14 16.

However, according to Carneiro-Proietti et al. (2002), the smoldering form may evolve to the acute form that is characterized by the presence of mature and immortalized CD4+ T cells. However, it is not known the causes that can trigger each clinical form of ATLL, but Yamagishi & Watanabe (2012) indicate that genetic and environmental factors may favor clinical development.

It was also observed that ATLL form with the best overall survival was smoldering with longer survival period and less associate with aggressive clinical conditions, so with the study by Akbarin et al. (2017). The acute form presented the highest death rate and one of the shortest survival times, as well as the PCT subtype. This outcome was similar to the results reported by Malpica et al. (2018) and this information is consistent with ATLL natural history.

Both the chronic and acute group, as for the PCT group, presented high levels of LDH, emphasizing that the last group had the highest level of LDH, when compared to the others. The high level of LDH may be linked to more aggressive symptoms and directly related with the evolution of the disease, which is consistent with the findings of the present assessment, thus proposing that high levels of LDH may be a good indicator evolution and clinical aggressiveness6 18 19 20. It is important to highlight that in ATLL there is skin involvement and that it can occur in any clinical condition, be it less or more aggressive. These skin manifestations may appear in various forms and in some cases may affect other organs1. In all the cases studied the individuals had dermatological lesions and in half of the cases evaluated, they were associated with another clinical condition. These showed advanced and aggressive ATLL form, which indicates that the clinical condition is an indicator of death evolution, as was also observed in the study by Akbarin et al (2017).

The HTLV-1 is known to cause immunosuppression of the immune system and when associated with other pathogens, such as opportunistic diseases, which are commonly reported in cases of ATLL, may indicate immune deficiency. Generally, individuals that denote these characteristics present more intense conditions and rapid evolution of the disease13 18. Evidence has shown that ATLL does not contain somatic mutant genes, which could explain its aggressiveness. However, it is evident that diseased cells have multiple molecular characteristics, such as genome deregulation and gene regulation, which are determinant factors for disease progression10.

It was observed a distinct pattern in the expression of molecular markers among ALL clinical pictures, suggesting that such behavior may reflect the pathway of clinical pathogenesis. It is generally observed that the ATLL phenotype is known to present simultaneous positivity for CD4 + CD25 +, as observed in the present study6 14.

The CD25 surface marker is the cytokine receptor IL2. Was reported that IL-2 was not observed in their analysis for ATLL patients, as for this population there is an overexpression of this cytokine, which is involved in several signaling pathways that contribute to ATLL17. However, in the present study, it was observed that for individuals with PCT was partial loss of CD25, indicating that there is a reduction in the presence of T helper lymphocytes, because one of the characterizations of this cell group is the expression of this marker. Chen et al (2010), report that the expression of peripheral blood surface marker molecules for some ATLL types can be produced independently of cytokines and in vitro these cells needed co-culture.

In the evaluation of the other markers were consistent with the study by Bazarbachi et al. (2011) and this group also reports that in cases of ATLL there is loss of expression of CD7 marker. The expression of HTLV-1 specific CD8 + T cells is described as mainly responsible for clearing infected cells and controlling viral load, however there is a possibility of inhibition of tax gene expression as an immune system escape mechanism24. Thus, it was shown that the frequency of tax-specific CD8 + cells were lower in individuals with ATLL23.

There was a tendency for combined the therapy administration of IFN and AZT, assuming that this therapeutic scheme was chosen, as the literature indicates that this form of treatment results in a better therapeutic response with a high initial response rate and possible survival control, which is often significantly longer18 21 24.

This study presents an epidemiological and immunophenotypic evaluation for the specific population evaluated, which came from the public services offered by Labimuno, with SUS support. The number of cases was reduced to 35, because this study required medical records, however many of them were not found on the SMART platform. Thus, there was a limitation in the sample number of the study, but as the evaluated population is considered rare, the statistical frequency presented confidence levels for the retrospective evaluation.

The present study concludes that individuals with ATLL presenting the clinical forms: acute and PCT may evolve faster for death, unlike the smoldering subtype. Death outcomes were more frequent in women, and in cases who presented T circulating cell clone of CD4 subpopulation and CD7 loss expression, as well as partial loss of CD5 and CD25. Treatment using the combination of IFN and AZT was the better therapy.