Vaccine Response to a Neo Polyssacharide Antigen Typhim Vi on the Identification of Secondary Immunodeficiencies in Hematological Malignancy

An increasing healthcare challenge in the management of hematological malignancy (HM) is secondary immunodeficiency (SID), either caused by the underlying malignancy or by treatments, including B-cell-targeting therapies. From January 2019, the EMA (European Medicines Agency) included the evaluation of specific antibody (Ab) responses to better select patients for immunoglobulin replacement therapy (IgRT). Antibody response to polysaccharide immunizations is primordial in the immunological evaluation of the patients and it is thought to be the first Ab response to be lost in the rising of an immunodeficiency. Clinically, an impaired polysaccharide response means that the patient may not be protected to new encounters with encapsulated bacteria, having therefore higher risk of severe or recurrent infections. We evaluated Ab responses to pneumococcal (PPV) and Salmonella typhi (TV) pure polysaccharide immunization in a cohort of 42 HM patients and 24 healthy controls. Pre-post specific Ab serum concentrations were measured by ELISA (Binding Site, UK), before immunizations and at 4 weeks. Globally, the prevalence of TV titers pre-immunization was lower (9%) compared to PPV pre-immunization titers (76%) (p