Endogenous immunoglobulins and sepsis: New perspectives for guiding replacement therapies.

The recently emerging concept of immunosuppression developing in the field of severe sepsis generated the need to measure circulating immunoglobulins as part of the necessary tests to evaluate immunocompetence status in patients suffering from this condition. Serum concentrations can be used as a surrogate marker of the final outcome and as a biomarker to explore the need for supplementation of the host with intravenous immunoglobulin preparations. Available evidence from recent clinical studies pinpoints the main observations. The first is that circulating IgM is a phenomenon associated with progression from severe sepsis to septic shock. Deficient kinetics of circulating IgM during the first 7 days following the start of vasopressors is linked with unfavourable outcome. The second is the development of immunoscores using low levels of IgM, IgG1 and IgA. These immunoscores can predict 28-day mortality with an odds ratio ranging between 3 and 5. Novel techniques for evaluating patient's immune status are shedding new light on the development of modern therapeutics where immunoglobulin replacement may be part of a personalised therapeutic approach.