Two Waves of Specific B Cell Memory Immunoreconstruction Observed in Anti-HHV1-3 IgG Kinetics after Hematopoietic Stem Cell Transplantation.

Abstract

Humoral memory and specific antibody levels depend on the kind of antigen and individual immunofactors. The presence of IgM antibodies or a fourfold rise in specific IgG levels are generally accepted as diagnostic factors in the serology of acute viral infections. This basic model is not adequate for the herpes virome, especially after hematopoietic stem cell transplantation (HSCT), due to continuous, usually multifocal antigenic stimulation, various donor serostatuses, immunosuppression, and individual immunoreconstitution. A case-control study was conducted to identify active infection cases of human herpesvirus (HHV) (from 300 diagnosed immunocompromised patients) and to evaluate historically associated humoral factors to look at outcomes. We considered only the data of patients with meticulous differential diagnosis to exclude other causes, and thereby to observe pathways and temporal relationships, not the statistical ones usually collected in cohorts. Despite the small number, such data collection and analysis methods avoid a number of biases and indicate cause and effect. In this observational study, a retrospective analysis of data from 300 patients with clinical diagnosis of herpes simplex virus (HSV) and varicella zoster virus (VZV) reactivation showed a number of biases. Two well-differentiated cases (confirmed by a Tzanck test) with various diseases and conditioning evolutions of immune parameters showed an interesting pathway. Exponential decreases in specific IgGs after HSCT preceded virus replication were observed, with a cytopathic effect (shingles, VZV encephalitis and HSV-induced mucositis). The minima (lowest IgG levels) before herpesvirus reactivation were 234.23 mIU/mL and 94 RU/mL for VZV and HSV, respectively. This coincided with a low CD4 titer, but without other infectious processes. Other immune response parameters such as Treg, cytotoxic T cells, and complement and total IgG level were the same as they were before the transplant procedure. Interestingly, a second wave of immunoreconstitution with an anamnestic antibody response was not always observed. It coincided with prolonged herpes viral infection. A patient with lymphocyte depletion in conditioning showed an earlier second wave of immunoreconstitution (6th vs. 14th month). As is typical for infancy, the kinetics of the IgG level is unique after HSCT (the decline phase is first). Host microbiome factors (e.g., HHV1-3-serostatus) should be taken into account to predict risk of non-relapse mortality and survival after HSCT. The levels of specific antibodies help in predicting prognoses and improve disease management. A lack of differentiation and the confusing bias of the assessor (i.e., observer selection bias) are the main obstacles in statistical HHV1-3 research. Such time-lapse case studies may be the first to build evidence of a pathway and an association between immune parameters and HHV disease.