Prolonged Agammaglobulinemia Despite Unaltered B-Cell Lymphopoiesis After Peritransplant-Rituximab Administration in a Child

Persistent Hypogammaglobulinemia after Receiving Rituximab Post-HSCT Is Not Caused by an Intrinsic B Cell Defect

In the setting of hematopoietic stem cell transplantation (HSCT), Rituximab (RTX) is used for the treatment and prevention of EBV-associated post-transplantation lymphoproliferative disease or autoimmune phenomena such as autoimmune hemolytic anemia (AIHA). Persistent hypogammaglobulinemia and immunoglobulin substitution dependence has been observed in several patients after RTX treatment despite the normalization of total B cell numbers. We aimed to study whether this is a B cell intrinsic phenomenon. We analyzed four patients with different primary diseases who were treated with myeloablative conditioning and matched unrelated donor HSCT who developed persistent hypogammaglobulinemia after receiving RTX treatment. They all received RTX early after HSCT to treat EBV infection or AIHA post-HSCT. All patients showed normalized total B cell numbers but absent to very low IgG positive memory B cells, and three lacked IgA positive memory B cells. All of the patients had full donor chimerism, and none had encountered graft-versus-host disease. Sorted peripheral blood naïve B cells from these patients, when stimulated with CD40L, IL21, IL10 and anti-IgM, demonstrated intact B cell differentiation including the formation of class-switched memory B cells and IgA and IgG production. Peripheral blood T cell numbers including CD4 follicular T-helper (Tfh) cells were all within the normal reference range. In conclusion, in these four HSCT patients, the persistent hypogammaglobulinemia observed after RTX cannot be attributed to an acquired intrinsic B cell problem nor to a reduction in Tfh cell numbers.

Persistent hypogammaglobulinemia due to immunoglobulin class switch impairment by peri-transplant rituximab therapy

Post-transplant lymphoproliferative disorder (PTLD) is one of the most serious complications of allogeneic hematopoietic stem cell transplantation (HSCT). Rituximab is effective for PTLD; however, rituximab can produce adverse effects, including hypogammaglobulinemia. Here, we present the case of an 18-year-old female with refractory cytopenia of childhood who developed persistent selective hypogammaglobulinemia with low immunoglobulin G (IgG) 2 and IgG4 levels and monoclonal protein after rituximab therapy against probable PTLD. Despite B-cell recovery, the serum IgG levels gradually declined, reaching < 300 mg/dL at 33 months after rituximab treatment. In addition, class-switched memory (CD27⁺IgD^-) B cells were limited in phenotypic analysis. These findings suggest that peri-HSCT rituximab may contribute to an abnormal B-cell repertoire induced by impaired immunoglobulin class switch.

Rituximab-associated Hypogammaglobulinemia in pediatric patients with autoimmune diseases

BACKGROUND

Despite the increased use of rituximab in treating pediatric patients with autoimmune diseases in the last decade, there are limited data on rituximab safety in those subjects who have a developing immune system. The objective of this study is to determine the prevalence of hypogammaglobulinemia in children with autoimmune disease receiving rituximab within the first three years of treatment in the pediatric rheumatology clinic at a tertiary care center.

METHODS

We conducted a retrospective chart review of 63 pediatric subjects who received rituximab for the treatment of their autoimmune disease. Immunoglobulin gamma (IgG) levels, immunosuppressive medication and the need for immunoglobulin replacement therapy were evaluated. Hypogammaglobulinemia was defined as a serum IgG level less than two standard deviations below the mean for age-matched healthy controls.

RESULTS

Twenty-eight patients (44%) were found to have hypogammaglobulinemia. Hypogammaglobulinemia occurred within the first six months of rituximab treatment in the majority of patients (22 out of 28). The occurrence of hypogammaglobulinemia varied based on the rituximab indication: 46% pediatric Systemic Lupus Erythematosus (SLE), 71% autoimmune CNS disease, 60% ANCA vasculitis, and 12% in the miscellaneous group. Autoimmune CNS disease had more severe hypogammaglobulinemia, more persistent and was associated with more frequent or severe infections. Three patients with autoimmune CNS disease and one with SLE were given IgG replacement therapy to prevent recurrent or severe infections.

CONCLUSIONS

The prevalence of hypogammaglobulinemia in rituximab treated children with autoimmune disease seems to be higher than published data for adults, especially for children with autoimmune CNS disease. The onset of hypogammaglobulinemia is usually within six months of initiation of rituximab therapy. We recommend: 1) obtaining an IgG level prior to starting rituximab; 2) close monitoring for hypogammaglobulinemia after the use of rituximab in pediatric patients and 3) early institution of immunoglobulin replacement therapy if patients develop recurrent infections.

Juvenile-onset systemic lupus erythematosus (jSLE) - Pathophysiological concepts and treatment options

The systemic autoimmune/inflammatory condition systemic lupus erythematosus (SLE) manifests before the age of 16 years in 10-20% of all cases. Clinical courses are more severe, and organ complications are more common in patients with juvenile SLE. Varying gender distribution in different age groups and increasing severity with younger age and the presence of monogenic disease in early childhood indicate distinct differences in the pathophysiology of juvenile versus adult-onset SLE. Regardless of these differences, classification criteria and treatment options are identical. In this article, we discuss age-specific pathomechanisms of juvenile-onset SLE, which are currently available and as future treatment options, and propose reclassification of different forms of SLE along the inflammatory spectrum from autoinflammation to autoimmunity.