Immunodeficiency Secondary to Prematurity, Pregnancy, and Aging

In this chapter we address three common scenarios often faced by clinical immunologists. In the first case, we explore the approach to an abnormal newborn screening of T-cell receptor excision circles (TREC) and the challenges it presents specifically for secondary causes of T-cell lymphopenia including prematurity, low birth weight, stress, etc. We highlight the importance of prompt evaluation and initiation of therapy in newborns with “presumed” SCID based on abnormal TRECs. The second case addresses third trimester of pregnancy transplacental immunoglobulin G transfer. Mothers with primary antibody immune deficiency on replacement immunoglobulin therapy must have a dosing adjustment to account for plasma expansion. Failure to do so can result in not only suboptimal maternal IgG levels but also lower baseline IgG levels in newborns placing both the mother and child at risk for infections. Finally, comorbid conditions often seen after the sixth to seventh decade of life raise concern for increased risk of thromboembolic events in patients on immunoglobulin replacement. Here we review the use of anticoagulation and the mode of immunoglobulin replacement therapy.