Immunoglobulin levels and lymphocyte response to mitogenic stimulation in children with malignant disease during treatment and follow-up

Lymphocyte counts predict optimal timing of chemotherapy reinitiation after antivirus treatment for herpes zoster in children with leukemia

Herpes zoster (HZ) is rare in healthy children, but more prevalent in those with leukemia. Optimal timing of chemotherapy reinitiation after HZ treatment is challenging because chemotherapy suppresses immunity and increases risk of HZ relapse. We aimed to optimize the timing of chemotherapy reinitiation after HZ therapy in children with leukemia. The study included 31 children with acute leukemia and HZ infection. General information, clinical symptoms, laboratory test results, duration of HZ treatment, and prognosis were compared with those of children with leukemia alone. Correlation analysis was performed for 20 children who restarted chemotherapy after HZ treatment. Of 31 children with leukemia and HZ, 67.74% had lesions at multiple sites. The median time from chemotherapy initiation to HZ onset was 14.1 (1.5-29.5) months. Among 27 children included in the follow-up, there was one case of HZ relapse. After excluding children who did not continue chemotherapy after HZ treatment, the median interval between completion of HZ therapy and chemotherapy reinitiation in the remaining 20 children was 8.00 (- 3 to 27) days. Lymphocyte counts (LY#) on restarting chemotherapy correlated inversely with HZ lesion healing time (p < 0.05). LY# at the time of HZ onset were lower than those pre- and post-onset, and lower than those in the control group (p < 0.05). In conclusion, children with leukemia have a good HZ prognosis, but an increased risk of HZ recurrence. LY# at the time of chemotherapy reinitiation may be a useful indicator for selecting the optimal interval between antiviral therapy completion and chemotherapy reinitiation.

Clinical use of polyvalent intravenous immunoglobulins during intensive polychemotherapy in children with acute lymphoblastic leukemia

BACKGROUND

Acute lymphoblastic leukemia (ALL) is seen in almost 30% of cases of cancer among children. Drop in absolute neutrophil count (ANC) and immunosuppression during chemotherapy are causing the significant increase in the risk of other complications, which can lead to prolonged hospitalization, higher costs of therapy and increased mortality.

METHODS

The analysis concerned 78 patients treated for ALL at the Department of Pediatric Oncology, Hematology and Transplantology. The indications for the use of immunoglobulins, the regimen of administration, the dose and adverse reactions were analyzed.

RESULTS

Intravenous immunoglobulins (IVIGs) were used in 66 (85%) of 78 patients. The standard risk group (SR) was represented by 10 (15%) patients, intermediate (IR) - 29 (44%), and high (HR) - 27 (41%). The most common were 1 and 2-day administrations - 60% and 28%, respectively, of transfusions. The spread of the IVIG doses used ranged from 43 mg to 882 mg/kg body weight. In the SR and IR groups, preparations were transfused at the reinduction stage, while in the HR-consolidation. Among the indications for IVIG, the most common was hypogammaglobulinemia-117 (42%), neutropenia-69 (25%) and infection-62 (22%). During the implementation of 279 patterns of immunoglobulin preparations, 8 (3%) post-transfusion reactions were registered.

CONCLUSIONS

The vast majority of ALL patients required immunoglobulin substitution during polychemotherapy. The supply of preparations is safe, however, there are no unambiguous guidelines regarding their dosage.

Immunization status in childhood cancer survivors: A hidden risk which could be prevented

BACKGROUND

A limited number of studies have examined the vaccine-specific antibody status of children with cancer. There are disagreements over the guidelines for postcancer immunization strategy.

METHODS

Our study was an observational, cross-sectional retrospective review of data collected on children who were seen in the outpatient clinic at King Abdullah Medical City, Oncology Center, Jeddah, the Kingdom of Saudi Arabia. Our aim was to evaluate the seropositive status to vaccine-preventable diseases: measles, mumps, rubella, diphtheria, tetanus, polio, and Haemophilus influenzae type B (HIB) in childhood cancer survivors at our center in order to plan future vaccination for these children and establish a simple revaccination schedule.

RESULTS

Forty-seven patients (21 boys and 26 girls) were included in the study. Age at the time of cancer diagnosis (mean±standard deviation) was 5.68±3.79 years and age at test sampling was 10.68±3.79 years. Acute leukemia was the most common cancer (49% of patients), followed by lymphoma (28%), brain tumors (13%), and solid tumors (10%). Treatment intensities (according to the Treatment Intensity Rating Scale, version 3.0; ITR-3) were 2, 3, and 4 for 26 patients (55%), 20 patients (43%), and one patient (2.1%), respectively. We found that 93% of our patients were considered seronegative (unprotected) for at least one vaccine-preventable disease. The seronegative rates for measles, mumps, rubella, diphtheria, tetanus, polio, and HIB were 46.8%, 36.2%, 36.2%, 46.8%, 61.7%, 17.1%, and 42.6%, respectively. Criteria including age at diagnosis, age at sampling, type of malignancy, and treatment intensity were not significantly different between seropositive and seronegative patients.

CONCLUSION

Seronegative rates for vaccine-preventable diseases were very high in childhood cancer survivors, which represented a subpopulation of high-risk patients who could benefit from revaccination. We suggest a universal revaccination approach for all childhood cancer survivors, which is easily applicable and of low cost.

Vacunación en etapa de vigilancia en niños con cáncer

Señor editor: El niño que recibe quimioterapia para el tratamiento del cáncer presenta un estado de inmunosupresión debido a la enfermedad y a la terapia antineoplásica. La quimioterapia suprime la respuesta inmune, efecto que es más marcado durante la quimioterapia de induccióny consolidación, y es moderado durante la quimioterapia de mantenimiento…

Immunreconstitution and infectious complications after rituximab treatment in children and adolescents: what do we know and what can we learn from adults?

Rituximab, an anti CD20 monoclonal antibody, is widely used in the treatment of B-cell malignancies in adults and increasingly in pediatric patients. By depleting B-cells, rituximab interferes with humoral immunity. This review provides a comprehensive overview of immune reconstitution and infectious complications after rituximab treatment in children and adolescents. Immune reconstitution starts usually after six months with recovery to normal between nine to twelve months. Extended rituximab treatment results in a prolonged recovery of B-cells without an increase of clinically relevant infections. The kinetic of B-cell recovery is influenced by the concomitant chemotherapy and the underlying disease. Intensive B-NHL treatment such as high-dose chemotherapy followed by rituximab bears a risk for prolonged hypogammaglobulinemia. Overall transient alteration of immune reconstitution and infections after rituximab treatment are acceptable for children and adolescent without significant differences compared to adults. However, age related disparities in the kinetic of immune reconstitution and the definitive role of rituximab in the treatment for children and adolescents with B-cell malignancies need to be evaluated in prospective controlled clinical trials.

Varicella zoster immune status in children treated for acute leukemia

Children treated for acute leukemia are at increased risk of severe infection with varicella zoster virus (VZV). We studied the VZV sero-status of children with acute leukemia prior to starting chemotherapy and after completion of chemotherapy. VZV sero-status was assessed using time resolved fluorescence immunoassay (TRFIA) before starting treatment and 6 months after completion of treatment. Prior to starting treatment for acute leukemia, a significant proportion of children (35%) are VZV seronegative. On completion of treatment most patients maintained protective VZV antibody levels; however, 35% had reduced/loss VZV antibody to a level considered non-protective and susceptible to VZV infection.

Guidelines on vaccinations in paediatric haematology and oncology patients

OBJECTIVE

Vaccinations are the most important tool to prevent infectious diseases. Chemotherapy-induced immune depression may impact the efficacy of vaccinations in children.

PATIENTS AND METHODS

A panel of experts of the supportive care working group of the Italian Association Paediatric Haematology Oncology (AIEOP) addressed this issue by guidelines on vaccinations in paediatric cancer patients. The literature published between 1980 and 2013 was reviewed.

RESULTS AND CONCLUSION

During intensive chemotherapy, vaccination turned out to be effective for hepatitis A and B, whilst vaccinations with toxoid, protein subunits, or bacterial antigens should be postponed to the less intensive phases, to achieve an adequate immune response. Apart from varicella, the administration of live-attenuated-virus vaccines is not recommended during this phase. Family members should remain on recommended vaccination schedules, including toxoid, inactivated vaccine (also poliomyelitis), and live-attenuated vaccines (varicella, measles, mumps, and rubella). By the time of completion of chemotherapy, insufficient serum antibody levels for vaccine-preventable diseases have been reported, while immunological memory appears to be preserved. Once immunological recovery is completed, usually after 6 months, response to booster or vaccination is generally good and allows patients to be protected and also to contribute to herd immunity.

Multivariate analysis of the relation between immune dysfunction and treatment intensity in children with acute lymphoblastic leukemia

BACKGROUND

Immunoreconstitution following childhood acute lymphoblastic leukemia (ALL) is a complex process during which various immune functions recover differentially. This process is difficult to elucidate since variables are interrelated and require simultaneous evaluation, rendering conventional statistical methods inappropriate.

PROCEDURE

We used principal components analysis (PCA) and projection of latent structures (PLS) to evaluate immune competence in 32 children treated for ALL. One or 6 months after completion of therapy, the relation between lymphocyte subpopulations, lymphocyte function and response to vaccination with tetanus, diphtheria and hemophilus influenzae, was investigated.

RESULTS

PCA demonstrated that increasing treatment intensity correlated with progressive immune dysfunction. Children treated with high intensity had poor response to vaccination associated with loss of humoral memory, decreased CD4(+) 45RA(+) T-lymphocytes and increased CD5+ B-lymphocytes. Patients treated with intermediate intensity had better preservation of humoral memory but decreased CD4(+) 45RA(+) T-cells. Patients with a low intensity regimen had similar vaccination response and lymphocyte levels as controls.

CONCLUSIONS

Our findings demonstrate the utility of PCA and PLS in detecting hidden structures in complex data and suggest that, even 6 months after therapy, patients treated with intermediate and high intensity have attenuated responses to de novo antigens whereas those with high intensity also respond poorly to recall antigens.

Measles, mumps, and rubella antibody status and response to immunization in children after therapy for acute lymphoblastic leukemia

Seventy-seven patients with acute lymphoblastic leukemia (ALL) who were in complete remission and whose therapies had been stopped for at least 6 months before enrollment in this study were retrospectively analyzed regarding their antibody status for measles, mumps, and rubella, with the aim to demonstrate the seropositivity rate after treatment in the authors' group. Each patient's serum samples were analyzed by enzyme-linked immunosorbent assay (ELISA) method to determine the antibody titers before and after immunization. Measles serology was available in 77 children; 45 (58%) were seronegative. Initial ages of measle-seronegative patients were statistically lower than those of seropositive cases (median 3.29 versus 4.91 years, respectively). Mumps serology was available in 76 children; 36 (47%) were seronegative. Mumps-seropositive cases tended to have more frequent previous history of infection than seronegative cases (55.0% versus 28.6%, respectively, P = .05). Rubella serology was available in 76 children, and 20 (26.3%) were seronegative. It was determined that initial ages of rubella-seronegative patients were statistically lower than those of seropositive cases (median 3.03 versus 4.32 years, respectively). The authors concluded based on the results of their study that at a median of 3.31 years after completion of chemotherapy for ALL, the majority of cases had antibody levels lower than protective values for measles (58.4%); however, these values were 47.3% for mumps and 26.3% for rubella. Seroconversion rates after measles (55%) and mumps vaccination (57.1%) were still low. However, in the available cases, relatively adequate response to rubella vaccination (92.3%) was observed.

Humoral immunity against hepatitis B, tetanus, and diphtheria following chemotherapy for hematologic malignancies: a report and review of literature

Malignancy and its treatment are major causes of secondary immunodeficiency in childhood. The authors investigated the effects of chemotherapy on humoral immunity against hepatitis B, tetanus, and diphtheria in children with hematologic malignancies. The authors recruited 54 patients with hematologic malignancies after the completion of chemotherapy (group A), 25 patients with newly diagnosed hematologic malignancies before initiation of chemotherapy (group B), and 74 healthy controls (group C). All participants had been vaccinated against hepatitis B, tetanus, and diphtheria according to the Iranian national vaccination scheme. Patients in group A achieved protective levels of diphtheria and hepatitis B antibodies significantly less frequently than the other 2 groups and protective levels of tetanus antibody significantly less frequently than group C (P <.05). After controlling for age, the association observed for tetanus lost its significance, but chemotherapy was a significant and independent predictor of failure to achieve protective levels of antibodies against diphtheria (odds ratio [OR] = 7.7, P < .001) and hepatitis B (OR = 3.13, P = .008). These results indicate that chemotherapy has independent adverse effects on vaccine-induced antibody protection against diphtheria and hepatitis B.

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.

Vaccinations in children treated with standard-dose cancer therapy or hematopoietic stem cell transplantation

Most children with cancer are immunocompromised during therapy and for a variable period after completion of therapy. They are at an increased risk of infections, including vaccine-preventable infections. There is a reduction in immunity to vaccine-preventable diseases after completion of standard-dose chemotherapy and after hematopoietic stem cell transplant. It is important to protect these children against vaccine-preventable diseases by reimmunization.

Revaccination of Children after Completion of Standard Chemotherapy for Acute Leukemia

BACKGROUND

After the treatment of patients with acute leukemia, there is a decrease in vaccine-specific antibody and an increased susceptibility to certain vaccine-preventable diseases. A simple revaccination schedule is warranted.

METHOD

Fifty-nine children (age, 1-18 years) who had completed standard chemotherapy in accordance with Medical Research Council of United Kingdom protocols were recruited. All children received a single dose of Haemophilus influenzae type b (Hib), tetanus, diphtheria, acellular pertussis, meningococcus C, polio, measles, mumps, and rubella vaccines > or = 6 months after completion of treatment. Antibody concentrations were measured before vaccination and 2-4 weeks and 12 months after vaccination.

RESULTS

Prevaccination antibody levels were protective for all patients for tetanus (geometric mean concentration [GMC], 0.13 IU/mL; 95% CI, 0.1-0.17 IU/mL), for 87% for Hib (GMC, 0.5 microg/mL; 95% CI, 0.37-0.74 microg/mL), for 71% for measles (GMC, 301 mIU/mL; 95% CI, 163-557 mIU/mL), for 12% for meningococcus C (geometric mean titer [GMT], 1:2.9; 95% CI, 1:2.2 to 1:3.9), and for 11% for all 3 poliovirus serotypes. Revaccination resulted in a significant increase in levels of antibody to each vaccine antigen, with 100% of patients achieving optimal antitetanus antibody concentrations (defined as > 0.1 IU/mL; 1.5 IU/mL; 95% CI, 1.1-2.1 IU/mL), 93% achieving optimal antibody concentrations to Hib (defined as > 1.0 microg/mL; 6.5 microg/mL; 95% CI, 5.1-8.2 microg/mL), 94% achieving optimal antibody concentrations to measles (defined as > or = 120 mIU/mL; 2720 mIU/mL; 95% CI, 1423-5198 mIU/mL), 96% achieving optimal antibody concentrations to meningococcus C (defined as > or = 1:8; 1:1000; 95% CI, 1:483-1:2064), and 85% achieving optimal antibody concentrations to all the 3 poliovirus serotypes (defined as > or = 1:8). For the majority of subjects, protection persisted for at least 12 months after vaccination.

CONCLUSION

Revaccination of children after standard chemotherapy is important, and protection can be achieved in the majority of these children using a simple schedule of 1 vaccine dose at 6 months after completion of leukemia 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.

Immune reconstitution after childhood acute lymphoblastic leukemia is most severely affected in the high risk group

OBJECTIVE

The aim was to examine the immune reconstitution after current chemotherapy for childhood ALL, with a special focus on finding immunologic variables that predict a poor immune response to vaccinations.

PROCEDURE

In a cross-sectional study of 31 children after treatment with the NOPHO ALL-1992 protocol peripheral blood lymphocyte subsets, T- and B-cell function in vitro and serum immunoglobulins (Ig) were measured. All patients were examined once, at 1 or at 6 months after cessation of chemotherapy, immediately before vaccination with DT and Hib.

RESULTS

Lymphocytes, T-cells, and CD4+ T-cells were low at 6 months after treatment. Naive T-cell subsets were more reduced than memory subsets. In the high risk (HR) ALL group, CD8+ T-cells were reduced at 6 months. NK-cells were low at 1 month, but normal at 6 months; however, the CD3+CD56+ (NKT) subset was reduced at both time points. Total B-cell number was low at 1 month, but normal at 6 months. A relative increase of CD5+ B-cells (B-1 cells) was evident, particularly in the HR group. Antigen-independent T- and B-cell function in vitro were affected at 1 month, but virtually normalized at 6 months. Serum IgM level was decreased at 1 month and IgG3 level was increased at 1 and 6 months.

CONCLUSIONS

This study shows that immune reconstitution after childhood ALL is slower than previously reported and emphasizes the influence of treatment intensity. The most intensively treated patients still have persistent abnormalities in T-, B-, and NK-cell subsets at 6 months post therapy and show a poor response to immunization with T-cell dependent antigens. In the HR group, routine re-immunizations before this time point are of limited benefit, and the effect of repeated vaccinations should be evaluated.

Intensive treatment for childhood acute lymphoblastic leukemia reduces immune responses to diphtheria, tetanus, and Haemophilus influenzae type b

OBJECTIVES

Immunity to diphtheria toxoid (D), tetanus toxoid (T), and Haemophilus influenzae type b (Hib) is affected in children with acute lymphoblastic leukemia (ALL). The aims were to examine immunity and to compare the response to immunization at 1 or 6 months after treatment.

METHODS

Thirty-one patients were immunized with DT and conjugated Hib vaccine (ActHib) at 1 month or 6 months after treatment of ALL with the NOPHO 92 protocol. Antibody levels were determined before and 3 weeks after vaccination. Specific T and Hib antibody-secreting cells of IgG/IgA/IgM isotypes were analyzed in peripheral blood using an ELISPOT technique.

RESULTS

All specific antibody levels decreased during ALL treatment, and protective levels after treatment were noted for 17% against D, 33% against T, and 100% against Hib. No high-risk patient had full D or T protection after treatment. After vaccination all the standard- and intermediate-risk patients achieved full protection against D, T, and Hib. The high-risk group showed insufficient immune response (full protection after vaccination: D 56%, T 22%, Hib 78%). No difference was found between vaccination at 1 month or 6 months after treatment. The poor antibody production in the high-risk group correlated to low numbers of antibody-secreting cells.

CONCLUSIONS

Nonprotective antibody levels against D, T, and Hib after childhood ALL are more common than previously thought. Insufficient immune response was restricted to the high-risk group and was related to a low number of memory B cells in this study. Immunizations should be included in follow-up after childhood ALL, and the policy should be adapted to treatment intensity.

Immunologic monitoring of maintenance therapy for acute lymphoblastic leukaemia in children-preliminary report

BACKGROUND

In the study we evaluated immune reconstitution during maintenance therapy for acute lymphoblastic leukaemia (ALL) in relation to different treatment protocols and response of the immune system to the accompanying infections.

PROCEDURE

The study group consisted of 40 children. The BFM protocol'90 was used in the standard risk group, while the New York protocol-in the high risk group. Assessment of the immune system was based on the analysis of peripheral blood mono-nuclear cells by flow cytometry and concentrations of immunoglobulins: G, M, A and IgE. Each patient was examined at 1-3 months' intervals.

RESULTS

Following cessation of intensive therapy, the successive months of maintenance treatment showed: (1) a considerable depletion of B lymphocytes, a durable decrease in IgM, IgA and gradually increasing IgG; (2) a correlation between the time passing from the cessation of intensive therapy and increased numbers and percentage of B cells, and the helper/suppressor cell ratio. In the group of children treated according to the high risk protocol, compared to the low-risk group patients, we found lower levels of the following parameters: IgG, % lymphocytes: B and T lymphocytes (including CD4/CD8 ratio and "naive"/"memory" ratio) and NK cells (% and count). During infection: (1) a significant increase was noted in the percentage of T cells with HLA co-expression and monocytes with ICAM-1 co-expression, (2) the percentage of CD3(+)CD45RO(+) "memory" T cells was found to increase.

CONCLUSIONS

Our findings indicate quantitative and qualitative changes of the immunity in children with ALL during maintenance therapy.

Significance of serum immunoglobulin G for leukocytosis and prognosis in childhood B-lineage acute lymphoblastic leukemia

BACKGROUND

This study was conducted to evaluate the significance of serum level of immunoglobulins (Igs) and particularly IgG for leukemic cell persistence in peripheral blood (PB) and prognosis for childhood acute lymphoblastic leukemia (ALL).

PROCEDURE

Human sera were obtained from 68 children with primary B-lineage ALL at diagnosis and 46 healthy children (control). Serum level of IgM, IgG, IgA, IgG1, IgG2, IgG3, IgG4, antitumor antibody, homogeneous IgG were quantified by turbidimetric or enzyme-linked immunosorbent assays.

RESULTS

The mean values of serum IgM, IgG, IgA at diagnosis were not differed significantly in ALL patients and control children. The level of IgM and IgG1 inversely correlated with white blood cell (WBC) count in PB of patients. Normal range of serum IgG, separated by 25th and 75th percentiles of IgG variables, was associated in patients with decreased WBC count in PB but not in bone marrow (BM) versus patients with low concentration of IgG. Normal range of IgG also favors low frequency of homogeneous IgG and antitumor antibodies. Patients with high level of IgG, besides increased frequency of homogeneous IgG and antitumor antibodies, had worse 3-year overall survival (OS) rate as compared to patients with normal level of IgG (58.8 vs. 91.2%, P = 0.014).

CONCLUSIONS

The normal level of serum IgG at diagnosis is a beneficial prognostic factor associated with lower rate of leukemic cell persistence in PB and better outcome of childhood B-lineage ALL.

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.

Current chemotherapy protocols for childhood acute lymphoblastic leukemia induce loss of humoral immunity to viral vaccination antigens

OBJECTIVE

To evaluate viral vaccination immunity and booster responses in children treated successfully for acute lymphoblastic leukemia by chemotherapy and to study the response to treatment of antibody-producing plasma cells that are important for persistence of humoral immunity.

METHODS

Forty-three children who were in continuous first remission for a median of 5 years (range: 2-12 years) were studied. Before the leukemia was diagnosed, all children had been immunized against measles, mumps, and rubella according to the Swedish National immunization program. We analyzed levels of serum antibodies against measles and rubella by enzyme immunoassays. Avidity tests for measles antibodies were concomitantly performed by enzyme-linked immunosorbent assay for measles virus immunoglobulin G detection. The proportion of plasma cells in bone marrow was studied by flow cytometry at different times during treatment and follow-up. Children who lacked protective levels of antibodies to vaccination antigens were reimmunized. Serum was collected 3 months after immunization to assess vaccination responses.

RESULTS

After completion of the treatment, only 26 of the 43 children (60%) were found to be immune against measles and 31 (72%) against rubella. The proportion of bone marrow plasma cells decreased during treatment but returned to normal after 6 months. Revaccination caused both primary and secondary immune responses. Six of the 14 children without immunity failed to achieve protective levels of specific antibodies against measles and 3 against rubella.

CONCLUSIONS

Our finding of loss of antibodies against measles and rubella in children treated with intensive chemotherapy suggests that reimmunization of these patients is necessary after completion of the treatment. To determine reimmunization schedules for children treated with chemotherapy, vaccination responses need to be studied further.

Transient pancytopenia preceding acute lymphoblastic leukaemia (pre-ALL) precipitated by parvovirus B19

A preleukaemic phase, typified by pancytopenia and bone marrow (BM) hypoplasia, is an uncommon but well-documented prelude to acute lymphoblastic leukaemia (pre-ALL) in children. Parvovirus B19 (B19) exhibits a marked tropism to human BM and replicates only in erythroid progenitor cells acting as a confounding, but treatable agent in immunocompromised patients. We present the first case of B19-associated pre-ALL characterized by severe and recurring transient pancytopenia in a child who developed ALL 5 months later. The advent of B19-specific IgG at the time of infection and the subsequent disappearance 1.5 years later has not previously been described. In this patient the observed cytopenias were probably the result of B19 acting in concert with the failing BM and B19 is possibly one of several factors capable of triggering the onset of pre-ALL.

Serum antibody levels and avidities to Escherichia coli O antigens and poliovirus type 1 antigen are increased in children treated for malignant disease

BACKGROUND

Treatment of malignant disease in children is often associated with low serum immunoglobulin and reduced specific antibody levels. The aim of this study was to investigate if the functional affinity of specific antibodies in serum and saliva is reduced as well and to evaluate if antigenic exposure or treatment duration affects this antibody avidity.

PROCEDURE

Serum samples were obtained from 45 children and salivary specimens from 30 children with malignant disease. The children were tested either prior to, during, or after chemotherapy. Levels of antibody to E. coli O and to poliovirus type 1 antigens were determined using an ELISA and isotype-specific relative antibody avidity was measured using thiocyanate to elute antibodies from solid-phase immobilized antigens.

RESULTS

Children with malignant disease had higher levels and relative avidity indexes of serum antibodies to both antigens as compared to controls. The duration of treatment and type of malignant disease were unrelated to these parameters. In saliva, the level of antibodies to E. coli O antigens, but not to poliovirus type 1 antigen, increased during treatment.

CONCLUSIONS

Both the amount and avidity of serum antibodies to these antigens are increased in children with malignant disease. This may be due to a dysregulation of the immune system caused by the malignancy and seems not to be dependent on exposure. In contrast, the avidity and levels of these antibodies in saliva seem to correlate with the presence of antigenic exposure.

Bone marrow immunoglobulin-secreting cells are not reduced in children with leukaemia as compared to children with solid tumours

Children with leukaemia exhibit multiple immunological disturbances, including low circulating levels of immunoglobulins, caused by both the disease and chemotherapy. We investigated the number of isotype-specific immunoglobulin-secreting cells (ISCs) in the bone marrow at the time of diagnosis in 32 children and during therapy in 12 children with leukaemia. We compared these to the number of ISCs in 17 untreated children with solid tumours and related the ISCs to serum immunoglobulin levels, lymphocyte subsets, response to mitogenic stimulation and serum cytokine levels. Bone marrow specimens were analysed for isotype-specific (immunoglobulins G, A and M) ISCs using the ELISPOT method. At the time of diagnosis, for all isotypes, the total number of ISCs per millilitre of bone marrow in children with leukaemia was no different from that in children with solid tumours. Chemotherapy significantly decreased the number of ISCs. The quantitative relationship between the different isotypes was unaffected by both tumour type and therapy. It can be concluded that in childhood leukaemia, tumour replacement of bone marrow cells does not cause a decreased number of ISCs and can therefore not account for the low serum immunoglobulin levels observed at time of diagnosis. Chemotherapy reduces the number of ISCs without changing the isotype distribution.