Beyond the M-spike - immunoparesis and multiple myeloma. A narrative review.

Secondary immunodeficiency or immunoparesis is an acquired impairment of the immune system which is a recognised feature of multiple myeloma (MM). Although classically described as a reduced production of polyclonal immunoglobulins, MM induces global immune dysfunction with defects in innate immune and T cell effector function. Immunoparesis can be detected in premalignant states, including monoclonal gammopathy of uncertain significance. Patients with immunoparesis have a poorer prognosis and present with severe, recurrent infection, which is associated with increased morbidity and mortality especially in the first 3 months following diagnosis, with relapse or progression and with the use of novel therapeutics. Bacterial infections, and specifically pneumonia, are the commonest presentation although there are increased risks of both viral reactivation and invasive fungal infection. Management of immunoparesis in MM includes the use of antimicrobial prophylaxis, and immunoglobulin replacement therapy particularly during high-risk periods. Although vaccination against encapsulated organisms, reactivation viruses, and circulating seasonal viruses is recommended, the response in MM may be suboptimal.