Long-term abnormalities in T and B lymphocyte function in children following treatment for acute lymphoblastic leukaemia

Molecular characterization of hepatitis B virus (HBV) isolated from a pediatric case of acute lymphoid leukemia, with a delayed response to antiviral treatment: a case report

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is effectively used as the first-line antiviral for chronic hepatitis B virus (HBV) infection in adults and children older than 12 years. To date, no confirmed case of virologic breakthrough (VBT) in a pediatric case has been reported.

CASE PRESENTATION

Here we describe a case of a 5-year old, asymptomatically infected with HBV infection two months after chemotherapy for precursor B acute lymphoblastic leukemia (ALL). Although the 5-year old male is South African, his family originated from Guinea. At the end of the one-year follow-up, the infection progressed to chronic HBV infection, with a high viral load. At 36 weeks (8 months) post-treatment with lamivudine (LAM), there was a partial virologic response (PVR) and after 61 weeks (14 months), he was switched to TDF rescue monotherapy. Even with TDF treatment, he still experienced VBT and subsequent PVR. The full-length genome of HBV isolated 78 weeks after the switch to rescue TDF monotherapy was sequenced and belonged to genotype E. In addition to the LAM mutations (rtS256G and rtM267L), missense mutations in B-cell, T-cell, HLA class I and II-restricted epitopes emerged, which were to evade and escape host surveillance, leading to delayed viral clearance, persistence and disease progression. Two further events of VBT occurred between weeks 113 and 141 of TDF rescue-therapy. Viral loads and liver enzymes are normalizing progressively with long-term therapy.

CONCLUSION

Although the host immune reconstitution may be delayed, prolonged TDF treatment was effective in treating this pediatric case of HBV infection with VBT and PVR.

Vaccination in children with cancer: a debate

Children with malignancy present an important alteration of the immune system functionality caused by the illness itself and by the therapy they undergo. Therefore, they are at high risk of contracting vaccine-preventable diseases and of developing important complications. Vaccinations represent valid devices against these infections but this condition involves two main problems: are vaccines safe in these patients? Are vaccines effective in these patients? The aim of this review is to discuss the principles of vaccination management in children with cancer.

How to manage vaccinations in children with cancer

The optimal use of routine childhood immunizations in children with malignancy is still a matter of debate. Despite their higher risk of contracting vaccine preventable diseases and of suffering important complications, there is little understanding of the magnitude of the possible benefit of administering active immunization in this population due to a paucity of clinical trial data. Our review focuses on the management of children with cancer and offers some suggestions regarding their vaccination schedules.

Humoral immunity to diphtheria, tetanus, measles, and hemophilus influenzae type b in children with acute lymphoblastic leukemia and response to re-vaccination

OBJECTIVE

Loss of immunity to previous vaccination and timing of re-vaccination in children receiving chemotherapy remains controversial. The aim of this study was to investigate the immunity to vaccine preventable diseases in children with acute lymphoblastic leukemia (ALL).

PROCEDURE

Sixty-one patients with ALL and 13 healthy siblings were enrolled. Three study groups included newly diagnosed patients (group 1), patients on maintenance chemotherapy (group 2), and patients that completed chemotherapy (group 3). Blood samples for baseline antibody titers were obtained from all the patients and controls. Patients in group 2 were vaccinated with diphtheria, tetanus, and hemophilus influenzae type b (Hib). Patients in group 3 and controls received the measles vaccine in addition to all the above vaccines. In groups 2 and 3, post-vaccination antibody titers were also obtained.

RESULTS

Patients and controls had no Hib vaccine during primary vaccination. After chemotherapy median antibody levels against diphtheria, tetanus, measles, and Hib were decreased but tetanus antibodies were still at the protective levels. Proportions of the patients with protective levels were 11.1%, 83.3%, 16.7%, and 16.7% for diphtheria, tetanus, Hib, and measles, respectively. Vaccination achieved protective antibody levels in 81%, 100%, 89.5%, and 70% of the patients for diphtheria, tetanus, Hib, and measles, respectively. Vaccine responses during maintenance were also satisfying.

CONCLUSION

We recommend re-vaccination after 3 months of cessation of chemotherapy. Administration of Hib vaccine may be beneficial after the first 3 months of maintenance chemotherapy especially in children with no primary vaccination followed by a second booster dose after cessation of therapy to increase immunity.

Longitudinal assessment of immunological status and rate of immune recovery following treatment in children with ALL

BACKGROUND

We prospectively evaluated the immunological status, immune recovery and risk of infection in pediatric ALL patients treated on the BFM 95 protocol.

PROCEDURE

Humoral and cellular immunity were evaluated in 72 children with ALL at the end of intensive therapy and values were compared to those at the completion of therapy and 6-monthly. Parameters investigated included lymphocyte subpopulation by flow cytometry, immunoglobulin levels by nephelometry, antibody titers to previous immunizations and delayed hypersensitivity with skin testing. Immune responses were correlated to duration of therapy, CNS radiotherapy, age and sex.

RESULTS

Humoral immunity was severely depressed by the end of intensive therapy with low immunoglobulin levels and CD19, improved after therapy cessation. Cellular immune responses were normal at the end of intensive treatment but declined significantly by the end of therapy and both CD4 and CD8 remained low at later evaluation points whereas CD4/CD8 ratio was increasing. Duration of therapy and CNS radiotherapy did not affect the rate of immune recovery whereas female had higher CD19, CD45RO, and IgM and children >7 years had higher CD19 and lower CD16 and CD3DR. Among immunized children, 86.7% maintained protective antibodies to MMR and 63% to polio. Despite impairment of immunity, infections outside the neutropenic periods were common viral illnesses.

CONCLUSION

Humoral immunity was depressed in children with ALL at the end of intensive therapy but began to recover after cessation of therapy. In contrast, cellular immunity declined significantly by the end of therapy and remained abnormal for at least 1 year post-therapy.

Immunodeficiency in children with acute lymphoblastic leukemia after completion of modern aggressive chemotherapeutic regimens

OBJECTIVE

To determine the prevalence, duration, and a potential cause of humoral defect(s) in children with acute lymphoblastic leukemia (ALL) at least 1 year after completion of chemotherapy.

STUDY DESIGN

Antibody titers for mumps, rubeola, rubella, tetanus and diphtheria toxoid, poliovirus serotypes 1, 2,and 3, Haemophilus influenzae type b, varicella, and hepatitis B were obtained from 100 children with ALL. Children with non-protective titers to these microbial antigens were re-vaccinated and re-studied after anamnestic vaccine challenge.

RESULTS

The percent of children with ALL who had protective titers was markedly less than that anticipated for immunized control subjects. Longitudinally, many titers fluctuate between protective and non-protective antibody responses after re-immunization. The chemotherapy protocol used did not affect the ability of these children to express protective antibody responses. T-, B-, and NK-cell numbers and proliferative responses to mitogens were all normal. Age correlated with titer results for certain vaccines.

CONCLUSIONS

Children in remission from ALL have a high prevalence of humoral immune defects that are not related to any specific chemotherapy regimen. This antibody deficiency may place children with ALL at risk for the development of these bacterial and viral diseases, even after completion of chemotherapy. Pediatricians, oncologists, or both should periodically monitor humoral immunity after chemotherapy and re-vaccinate these children, as needed, to ensure prolonged immunoprotection.

Decrease of CD4 + and B-Lymphocyte Populations Is Not Associated with Severe Infectious Complications in Children with Acute Lymphoblastic Leukemia during Maintenance

The suppression of lymphopoiesis and immune competence during the maintenance phase in children with acute lymphoblastic leukemia (ALL) and the occurrence of infectious complications remain an unexplored area. In this study we assessed lymphocyte subpopulation disturbances during maintenance for childhood ALL along with the incidence, type, and severity of infections that occur during that period in the absence of neutropenia. Twenty-eight children (13 boys, 15 girls) with ALL aged 3-14 years (median 7 years) and treated according to the ALL-BFM 90/95 protocol were studied during maintenance for ALL. Complete white blood cell (WBC) counts and peripheral blood lymphocyte (PBL) analyses were performed. Major lymphocyte subsets (CD19+, CD3+CD4+, CD3-CD8+, CD3-CD16+CD56+, CD45RA-, CD45RO+) and markers of T-cell activation (CD25, CD38, CD69, HLA-DR) were analyzed with flow cytometry. Serum immunoglobulin G (IgG), IgA, and IgM levels were measured by a nephelometric assay. All infectious episodes during the study period were recorded in detail. Additionally, 41 age-matched immunocompetent children were used as controls. Absolute WBC counts (median, 3627/microL) and PBL counts (median, 1206/microL) were significantly below the age-adjusted control values (7400/microL and 2673/microL, respectively; P < .0001). B-lymphocyte, total CD4+, and memory CD4+ (CD4+CD45RO+) subsets were also significantly decreased (33/microL versus 377/microL [P < .0001], 531/microL versus 1045/microL [P < .01], and 80/microL versus 299/microL [P < .001], respectively). Significantly lower immunoglobulin levels were found in all patients. Twenty-two of the 28 patients presented with 74 episodes of a variety o minor infections (mostly respiratory viral [39], skin [7], and gastrointestinal [3]), none demanding prolonged hospital treat ment. Our findings demonstrate a profound immunosuppression throughout maintenance therapy in children with ALL tha has no major clinical impact in terms of increased incidence or severity of systemic infections.

Serologic study on parvovirus b19 infection in childhood acute lymphoblastic leukemia during chemotherapy: clinical and hematologic implications

PURPOSE

To present a first descriptive serologic study on the clinical and hematologic implications of parvovirus B19 (B19) infection in children with acute lymphoblastic leukemia from the time of initial admission until discontinuation of chemotherapy.

PATIENTS AND METHODS

Seventy-five patients were studied by polymerase chain reaction, enzyme-linked immunosorbent assay, sequencing, and immunodiffusion.

RESULTS

During the period of observation, 8% (4/48) of B19-seronegative patients seroconverted and infection triggered profound anemia and thrombocytopenia. B19-specific IgG disappeared in 26% (8/31) of B19-seropositive patients, and these patients were significantly younger and the B19 IgG titers were lower on admission compared with patients who continuously displayed B19 IgG. B19 DNA was detected in the seroconverting patients, and this helped in determining the time of infection, which coincided with a B19 epidemic in 75% (3/4) of patients. Patients typically presented with fever and myalgia; a rash, indicative of B19 infection, was observed in only one patient.

CONCLUSIONS

B19 infection was able to mimic a leukemic relapse or therapy-induced cytopenia and led to hospital admission, frequent blood sampling, renewed bone marrow aspirates, multiple transfusions of red blood cells or platelets, and cessation of maintenance chemotherapy for up to 3 weeks. The peculiar disappearance of B19-specific IgG, which could not be ascribed to a generalized low level of serum immunoglobulins, has not been previously reported. The results indicate that B19 should be assayed at diagnosis of leukemia to avoid subsequent diagnostic uncertainty, and during treatment in B19-seronegative patients exhibiting unexplained cytopenia.

Intact T-cell regenerative capacity in childhood acute lymphoblastic leukemia after remission induction therapy

BACKGROUND

Acute lymphoblastic leukemia (ALL) is a bone marrow disease. This may adversely affect the capacity of T cells to recover from chemotherapy-induced T-cell depletion and thus contribute to the prevailing immune deficiency in ALL patients.

PROCEDURE

We tested the capacity of T-cells to regenerate in 18 ALL children in first clinical remission (median age 4.2 years) at the time of hematologic reconstitution after BFM-ALL induction therapy (treatment-free interval 22 days, median; range 12 to 52 days). All patients had experienced a period of leukopenia (white blood cell count [WBC] <0.95 x 10(9)/l, median) during the final four weeks of induction therapy. T-cells and T-cell subsets were examined by FACS.

RESULTS

At the time of investigation the WBC was near normal (3.5 x 10(9)/l, median). Surprisingly, most cases (78%) showed a complete regeneration of T-cells and its subsets including 1) normal total (CD3+) T-cells (1635/microl, median; range 756-3440/microl); 2) normal T-helper (CD4+) cells (697/microl, median; range 128-1523/microl); and 3) normal T-cytotoxic/suppressor (CD8+) cells (686/microl, median; range 348-1540/microl). Eight patients achieved a normal CD4+/CD8+ ratio (0.8, median). Subset analyses of T-helper cells revealed a normal proportion of CD4+CD45RA+ cells (52%, median) in all but one patient below the age of 6 years, indicating an intact residual thymic activity. No correlation was observed between age at diagnosis and a normal CD4+ count (r = 0.086) or between a normal CD4+ count and a normal proportion of CD4+CD45RA+ cells r = 0.136). A long-term survey in four patients showed altered T-cells after reinduction and during maintenance therapy.

CONCLUSIONS

The findings suggest that ALL per se does not inhibit T-cell regenerative capacity. Thus, the frequently observed longlasting impairment of the T-cell system in ALL is attributable to the treatment rather than to the underlying disease.

Immune recovery in children with malignancy after cessation of chemotherapy

PURPOSE

To study longitudinally the extent and recovery of cellular and humoral immune alterations in children with cancer after completion of their therapy.

PATIENTS AND METHODS

Using standard immune assays, cellular and humoral immunity was measured in 43 infants and children with cancer at completion of therapy and every 3 months thereafter for 1 year. There were 17 patients with acute lymphoblastic leukemia, 9 with Hodgkin disease, and 17 with solid nonhematopoietic tumors. All children had received standard childhood immunizations before diagnosis of cancer. Immune assays performed included circulating lymphocyte subpopulations, in vitro antigen-induced responses, and total concentrations of serum immunoglobulin G (IgG), IgM, IgA, and IgG subclasses, and specific antibodies against diphtheria, tetanus, pertussis, and poliovirus types I, II, and III.

RESULTS

At completion of therapy, the majority of patients had low circulating lymphocyte subpopulations and antigen-induced responses. Serum antibody concentrations were low in up to 89% of patients regardless of the underlying malignancy. Although improvement occurred during the year of follow-up, 35 of 43 (81%) patients continued to exhibit one or more immune abnormalities 9 to 12 months after cessation of chemotherapy. Younger patients had more persistent alterations. Other risk factors studied (including gender, duration of therapy, and underlying malignancy) did not correlate with the severity of the immune defects. With the exception of poliovirus antibodies, specific antibody titers against common childhood vaccine antigens were deficient at completion of therapy and 9 to 12 months later in a substantial proportion of patients.

CONCLUSION

Children with malignancy have persistent specific and nonspecific immune alterations 9 to 12 months after cessation of chemotherapy. The clinical implications of these in vitro observations are unclear and require further evaluation.

Immunodeficiency in long-term survivors of acute lymphoblastic leukemia treated with Berlin-Frankfurt-Münster therapy

OBJECTIVE

To determine whether the immune systems of long-term survivors of acute lymphoblastic leukemia (ALL) have persistent immune defects after Berlin-Frankfurt-Münster (BFM) treatment.

STUDY DESIGN

We evaluated the cellular and humoral immune responses of 13 children with ALL in complete remission and off modified protocol treatment for 2 or more years. All patients had received complete immunizations for measles, mumps, rubella, and poliovirus before ALL developed. They were challenged with Haemophilus influenzae type B (Hib) and Pneumococcus vaccines after baseline serum samples were obtained. We also determined in vivo humoral immune responses to bacteria and viruses that cause common pediatric diseases.

RESULTS

Compared with age-matched control subjects, the long-term survivors of ALL had a significant difference in the presence of protective antibodies to measles (p < 0.0001) and polioviruses (p < 0.0001) in their baseline sera; more than half had no protective antibodies to one or more previously administered vaccines or related infections. Most produced protective concentrations of specific antibody after reimmunization, but some were repeatedly unable to make protective antibodies, or mount a normal antibody response, despite natural disease and/or revaccination. Four children had significant infections.

CONCLUSIONS

Long-term survivors of ALL who had BFM treatment may have persistent immune defects with respect to common childhood bacterial and viral diseases they previously had, or vaccines they received.

Maintenance chemotherapy and cure of childhood acute lymphoblastic leukaemia

Maintenance chemotherapy with 6-mercaptopurine and methotrexate, widely believed an essential contribution to the high cure rates achieved in children with acute lymphoblastic leukaemia (ALL), is thought to work by killing the leukaemia cells that remain after intensive chemotherapy. We suggest instead that ALL commonly arises in precursor B cells normally programmed to die, and that maintenance chemotherapy does not kill these cells but controls growth of the leukaemia clone so that programmed death can occur. A similar approach may apply to other cancers in which programmed death is intrinsic to the normal counterparts of the neoplastic cells.

Late effects of childhood acute leukemia and its treatment

Late effects of childhood acute leukemia and its treatment were studied in 776 patients (684 ALL, 73 ANLL, and 9 others) in Japan who had remained in remission for more than 1 year after their first complete remission. Delayed adverse sequelae involve a wide variety of organs and their functions. Short stature was present in 2.61%, obesity in 3.79%, abnormalities of growth hormone secretion in 1.5%, delayed secondary sex characteristics in 1.5% of males and 0.6% of females, motor disturbances in 1.17%, sensory disturbances in 0.91%, intellectual and learning disabilities in 2.48%, abnormal findings in routine neurologic examinations in 1.31%, EEG abnormalities in 4.30%, brain CT abnormalities in 5.09% and cardiac dysfunction in 1.07%. Various other disorders were seen in 20 patients. Many of these delayed adverse sequelae are caused by or related to central nervous system prophylaxis and systemic combination chemotherapy. The results suggest that it is needed to improve therapeutic methods through the stratification of patients by risk factors and detailed analysis of prognostic factors. Moreover it is important to render medical and psychosocial support to long-term survivors of childhood leukemia through interactions between the patient, parents and medical staff.

Spontaneous natural killer cell activity in childhood acute lymphoblastic leukaemia

Endogenous NK activity was measured in ALL patients and compared with child and adult control values. ALL children undergoing maintenance chemotherapy showed significantly lower NK activity than control groups; however, patients off treatment and in remission expressed cytotoxicity within the normal range of the control groups. The expression of the HNK-1 marker in the ALL children was not significantly different from child controls, although ALL patients failed to show the same correlation between cytotoxic activity and HNK-1 expression. The target binding capacity of PBLs from ALL children was significantly greater compared with controls but did not correlate with NK activity. In addition plasma from ALL patients was not inhibitory for NK cytolytic activity, suggesting an innate defect in cytotoxicity mediated by NK cells rather than a plasma inhibitory factor. Patients failing to display NK activity against K562 target cells appeared to mediate killing of measles virus infected (Raji) targets.

Immunological competence of patients in remission from acute leukaemia: apparently normal T cell function but defective pokeweed mitogen-driven immunoglobulin synthesis

Immunological function of 62 patients in remission from acute leukaemia has been evaluated using peripheral blood mononuclear cells in vitro assays. T cell function, as indicated by proliferation in response to polyclonal activation (by phytohaemagglutinin) and antigen-specific stimulation (allogeneic cells), was normal in these patients. In contrast, pokeweed mitogen-driven Ig synthesis was significantly decreased for all immunoglobulin classes measured (IgM, IgG and IgA) in the case of adult and childhood acute lymphocytic leukaemia patients, and for IgA in the case of adult acute non-lymphocytic leukaemia patients. The defects in humoral immunological responses may contribute to the increased susceptibility to infection of these patients.

Effect of methotrexate on the immune response in children with acute lymphatic leukaemia

Lymphocyte count, lymphocyte subpopulations identified by monoclonal antibodies and mitogen stimulation assays with phytohaemagglutinin, concanavalin A, pokeweed mitogen and staphylococcal protein A, were used to quantitate the effect of methotrexate on the immune response in children with acute lymphatic leukaemia on maintenance therapy. Methotrexate exerted a profound but apparently short-term effect on these parameters as it is prescribed in current maintenance schedules for childhood acute lymphatic leukaemia. A significant drop in lymphocyte count, affecting all subpopulations, was observed 4 h after oral or intramuscular administration of methotrexate which had reverted to pre-methotrexate values one week after the drug was given. Lymphocyte function was markedly affected, with a major decrease in mitogen responsiveness 1 h after methotrexate and a reversion to pre-methotrexate values by 48 h. A selectivity of suppressor T cells to methotrexate is proposed as being responsible for early recovery. Scheduling of methotrexate in current maintenance programmes would therefore appear to allow adequate time for recovery of immunoresponsiveness between doses.

Abnormalities of myeloid progenitor cells after "successful" bone marrow transplantation

We studied recovery of peripheral blood- and bone marrow-derived myeloid progenitor cells (CFU-G,M) in 29 patients who received bone marrow transplants 2 mo to 8.5 yr previously. All patients had normal levels of peripheral blood neutrophils, normal bone marrow cellularity, and a normal myeloid-erythroid ratio. Both peripheral blood- and bone marrow-derived CFU-G,M were markedly reduced compared with normal controls and bone marrow donors [5 +/- 1/10(6) vs. 37 +/- 4/10(6) (P less than 0.001) and 23 +/- 5/2 x 10(5) vs. 170 +/- 21/2 x 10(5) (P less than 0.001)]. Five patients had no detectable CFU-G,M even when 10(6) bone marrow cels were plated. These abnormalities of CFU-G,M were unrelated to age, sex, diagnosis, conditioning regimen, dose of bone marrow cells transplanted, and presence or absence of graft-vs.-host disease. Patients who received either autotransplants or transplants from identical twins also had decreased or absent CFU-G,M indicating that allogeneic factors and posttransplant immune suppressor with methotrexate or corticosteroids were not major determinants of this abnormality. Co-culture of normal or donor peripheral blood or bone marrow mononuclear cells with recipients peripheral blood or bone marrow mononuclear cells, purified T cells, or serum failed to show any evidence of active CFU-G,M suppression. Furthermore, the abnormality of CFU-G,M could not be corrected by the addition of normal syngeneic (donor) hematopoietic cells or serum. Depletion of T-cells from recipient bone marrow by physical techniques resulted in marked increase in CFU-G,M (36 +/- 13 vs. 138 +/- 36; P less than 0.05). The abnormality could be reproduced in vitro by readdition of autologous T cells. In contrast to results with T cell depletion by physical techniques, T cell depletion with a monoclonal anti-T antibody (B7) and complement had no effect. These data indicate that most-transplant recipients have a marked abnormality in CFU-G,M when these cells are cultured in vitro. In at least some of these patients, the decreased cloning efficiency of CFU-G,M appears to be mediated by a suppressive effect of autologous T cells.

Modulation of cellular immune function by cyclophosphamide in children with minimal-change nephropathy

Cyclophosphamide is widely used to induce a remission of minimal-change nephropathy, but concerns have been raised about whether its effects on cellular immunity persist after treatment is discontinued. We studied functional and numerical measures of cellular immunity in children who had minimal-change nephropathy with frequent steroid-responsive relapses and were receiving cyclophosphamide (2.5 mg per kilogram of body weight per day for eight weeks). Sequential studies during such treatment showed that cyclophosphamide caused lymphopenia, particularly among T helper cells, resulting in a significant fall in the immunoregulatory (helper/suppressor) cell ratio. This change persisted 1 to 3 months after cyclophosphamide was discontinued, but measures of immune function reverted to normal after 6 to 12 months. Children with minimal-change nephropathy in long-term remission had no difference in T-cell subpopulations, lymphocyte responses to mitogens, or suppressor-cell function that could be attributed to the disease itself or to the previous use of cyclophosphamide.