Patients with MM are more susceptible to infections due to disease-related factors (suppression of cellular and humoral immunity, including hypogammaglobulinemia lymphocyte dysfunction, low CD4+ cell count and impaired function of natural killer cells), patient-related factors (old age, poor performance status, and comorbidities, including diabetes mellitus and renal dysfunction) and treatment-related factors (neutropenia) (11, 12) especially within the first year of diagnosis (11). This evidence concerns the gene CD4 and infection.