Too Often Forgotten: Passive Transfer of Antibodies

Immunoglobulin treatment for B-cell immunodeficiencies

This article aims to describe the rationale and utility of immunoglobulin therapies in patients with B-cell immunodeficiency states. We describe the historical perspective, mechanism of actions, and indications for use in this population. We then focus upon management pearls and special considerations for its utility. Finally, we elaborate upon the important economic implications for these patients and the need to develop individualized management strategies in this vulnerable population.

Management of Myeloma Manifestations and Complications: The Cornerstone of Supportive Care: Recommendation of the Canadian Myeloma Research Group (formerly Myeloma Canada Research Network) Consensus Guideline Consortium

Multiple myeloma (MM) is a hematological cancer associated with significant symptomatic burden. Bone disease, renal insufficiency, cytopenias, infection, and peripheral neuropathy, among other disease manifestations and complications, impair patients' quality of life. The Canadian Myeloma Research Group Consensus Guideline Consortium, formerly Myeloma Canada Research Network Consensus Guideline Consortium, proposes national consensus recommendations for the management of MM-related manifestations and complications. To address the needs of Canadian physicians and people living with MM across the country, this document focuses on the improvement and maintenance of patient care by clarifying best-practice approaches for the prevention, detection and management of disease manifestations and complications. The Canadian Myeloma Research Group Consensus Guideline Consortium will periodically review the recommendations herein and update as necessary.

Antibodies against vaccine-preventable infections after CAR-T cell therapy for B cell malignancies

BACKGROUND

Little is known about pathogen-specific humoral immunity after chimeric antigen receptor–modified T (CAR-T) cell therapy for B cell malignancies.

METHODS

We conducted a prospective cross-sectional study of CD19-targeted or B cell maturation antigen–targeted (BCMA-targeted) CAR-T cell therapy recipients at least 6 months posttreatment and in remission. We measured pathogen-specific IgG against 12 vaccine-preventable infections and the number of viral and bacterial epitopes to which IgG was detected (“epitope hits”) using a serological profiling assay. The primary outcome was the proportion of participants with IgG levels above a threshold correlated with seroprotection for vaccine-preventable infections.

RESULTS

We enrolled 65 children and adults a median of 20 months after CD19- (n = 54) or BCMA- (n = 11) CAR-T cell therapy. Among 30 adults without IgG replacement therapy (IGRT) in the prior 16 weeks, 27 (90%) had hypogammaglobulinemia. These individuals had seroprotection to a median of 67% (IQR, 59%–73%) of tested infections. Proportions of participants with seroprotection per pathogen were comparable to population-based studies, but most individuals lacked seroprotection to specific pathogens. Compared with CD19-CAR-T cell recipients, BCMA-CAR-T cell recipients were half as likely to have seroprotection (prevalence ratio, 0.47; 95% CI, 0.18–1.25) and had fewer pathogen-specific epitope hits (mean difference, –90 epitope hits; 95% CI, –157 to –22).

CONCLUSION

Seroprotection for vaccine-preventable infections in adult CD19-CAR-T cell recipients was comparable to the general population. BCMA-CAR-T cell recipients had fewer pathogen-specific antibodies. Deficits in both groups support the need for vaccine and immunoglobulin replacement therapy studies.

FUNDING

Swiss National Science Foundation (Early Postdoc Mobility grant P2BSP3_188162), NIH/National Cancer Institute (NIH/NCI) (U01CA247548 and P01CA018029), NIH/NCI Cancer Center Support Grants (P30CA0087-48 and P30CA015704-44), American Society for Transplantation and Cellular Therapy, and Juno Therapeutics/BMS.

In this prospective study, we investigated antibodies against vaccine-preventable infections and other pathogen-specific antibodies in individuals with remission after CAR-T cell therapy for B lineage malignancies.

Immunoglobulin Preparations Can Mislead Clinical Decision-Making in Follow-Up of Differentiated Thyroid Cancer

OBJECTIVE

Intravenous and subcutaneous immunoglobulins are commonly used for immune substitution or as immune modulators in a variety of inflammatory and autoimmune disorders. Exogenous thyroid-specific thyroglobulin (Tg) antibodies present in the donor plasma may interfere with the interpretation of measurements of Tg autoantibodies (Tg-Abs) in the recipient's plasma and potentially trigger an immune response in the recipient's immune cells. Levels of antibodies causing bioassay interferences or those leading to clinically relevant changes in patient outcomes are not known. Tg is used as a biomarker in the long-term surveillance of patients with differentiated thyroid cancer (DTC) following total thyroidectomy and radioactive iodine ablation. However, the presence of Tg-Abs in the circulation interferes with Tg measurements. Assessment of levels of Tg-Abs is thus recommended as a part of standard follow-up of DTC together with Tg testing.

METHODS

To understand the potential mechanisms and pathophysiologic significance of possible interferences associated with administration immunoglobulin preparations and Tg measurement, we overview the current knowledge on interactions between Tg autoimmunity and immunoglobulin preparations and illustrate diagnostic challenges and perspectives for follow-up of patients with DTC treated with exogenous immunoglobulins.

RESULTS

In patients with DTC treated with immunoglobulin preparations, monitoring of thyroid cancer using Tg and Tg-Abs is challenging due to possible analytical interferences through passive transfer of exogenous antibodies from immunoglobulin preparations.

CONCLUSION

Analytical interferences must be suspected when a discrepancy exists between clinical examination and diagnostic tests. Collaboration between endocrinologists, biologists, and pharmacologists is fundamental to avoid misdiagnosis and unnecessary medical or radiologic procedures.

ABBREVIATIONS

CT = computed tomography; DTC = differentiated thyroid cancer; FNAB = fine-needle aspiration biopsy; HAb = heterophile antibody; IMA = immunometric assay; IVIg = intravenous immunoglobulin; RAI = radioactive iodine; RIA = radioimmunoassay; SCIg = subcutaneous immunoglobulin; Tg = thyroglobulin; Tg-Ab = thyroglobulin autoantibody; Tg-MS = thyroglobulin mass spectrometry; TPO-Ab = thyroid peroxidase autoantibody; TSHR-Ab = thyrotropin receptor autoantibody.

Interpretation and management of positive anti-hepatitis B core antibody tests in immunocompromised pediatric patients

Intravenous immunoglobulin (IVIg) therapy is increasingly used in the pediatric population, in particular among children with immune-compromising conditions. Pooled immunoglobulin products are routinely tested for hepatitis B surface antigen (HBsAg) and nucleic acid; however, screening for hepatitis B core antibody (anti-HBc) is not commonly performed. Thus, the administration of IVIg containing anti-HBc to children with immune-compromising conditions may complicate the interpretation of hepatitis B serologic testing in that a positive anti-HBc test may represent passive transfer of antibody from IVIg or may indicate resolved or chronic hepatitis B infection. Due to the risk of hepatitis B reactivation in immunocompromised patients, a positive anti-HBc test must be carefully considered. As part of a quality improvement initiative, we identified and reviewed the records of all pediatric patients at our institution who tested positive for anti-HBc over an 18-month period. Of 44 total patients with positive anti-HBc tests, we found that 22 (50%) had previously received IVIg in the preceding 4 months. All but one of these, 21/22 (95%), went on to receive immunosuppressive therapy (IS). Among the patients who received IS, 19 (86%) had not undergone hepatitis B serologic testing prior to IVIg administration and 16 (73%) did not have subsequent testing to distinguish between passive acquisition of anti-HBc from IVIg and chronic hepatitis B infection. Our single-center experience reveals that a high proportion of positive anti-HBc tests in children are presumed to be because of the passive antibody transfer from IVIg. However, a low proportion of patients undergo confirmatory testing, despite the risk of hepatitis B reactivation during IS. We thus propose a risk-based algorithm for interpretation and monitoring of hepatitis B testing in immunocompromised children.

Passive transfer of anti-HBc after intravenous immunoglobulin administration in patients with cancer: a retrospective chart review

BACKGROUND

Patients previously infected with hepatitis B virus (HBV; indicated by positivity for anti-HBc) can experience HBV reactivation during cancer chemotherapy. Intravenous immunoglobulin infusion, which is frequently used in supportive care, might facilitate passive transfer of anti-HBc. We aimed to estimate the probability of passive transfer of anti-HBc after intravenous immunoglobulin infusion in patients with cancer.

METHODS

We reviewed institutional databases to identify adult patients who received outpatient chemotherapy between Jan 1, 2004, and Dec 31, 2011, at the University of Texas MD Anderson Cancer Center, Houston, TX, USA. Eligible patients had received intravenous immunoglobulin therapy, had tested negative for both anti-HBc and HBsAg before infusion, and had been tested for anti-HBc after infusion. The primary endpoint was the proportion of patients who became positive for anti-HBc after intravenous immunoglobulin infusion.

FINDINGS

950 of 18 874 patients who underwent chemotherapy within the study time frame received intravenous immunoglobulin, of whom 870 had been tested for anti-HBc before infusion. 199 patients who were negative for anti-HBc before receiving intravenous immunoglobulin were retested after infusion, of whom 29 (15% [95% CI 10-20]) became positive for anti-HBc. The probability of anti-HBc conversion at 1 week after intravenous immunoglobulin infusion was 34% (95% CI 22-48) and at 12 weeks was 4% (2-7).

INTERPRETATION

Conversion of patients from anti-HBc negativity to anti-HBc positivity was common after intravenous immunoglobulin administration. However, the probability of a positive test decreased with time since infusion. Positive anti-HBc tests done shortly after intravenous immunoglobulin infusion should be interpreted with caution because they might indicate passive transfer instead of true infection.

FUNDING

None.

False positive viral marker results in blood donors and their unintended consequences

False positive (FP) viral marker results in blood donors continue to pose many challenges. Informing donors of FP results and subsequent deferral can result in stress and anxiety for donors and additional complexity and workload for blood services. Donor management strategies need to balance the requirement to minimise donor anxiety and inconvenience while maintaining sufficiency of supply. Decisions about how and when to inform donors of FP results and determine deferral periods can be difficult as FP results, while often transitory, can take up to several years to resolve. Additional complexities include the interpretation of indeterminate serological confirmatory testing without detectable viral RNA or non-discriminated NAT results with concomitant anti-HBc reactivity - both may be due to FP results, but the former may also represent past infection and the later may represent occult hepatitis B infection. In this review we discuss strategies to minimise indeterminate serological confirmatory results, possible donor deferral policies and the impact on donors when notified of FP results. We also provide some new data from Australia that address the challenge of interpreting non-discriminated NAT results with concomitant anti-HBc reactivity. Ultimately, the challenge is for each blood service to develop appropriate strategies for donor management, taking into account local information and requirements.