Chapter 42: The Child With an Immunologic Alteration

The immune response comprises two interconnected systems: innate immunity, which provides immediate nonspecific defense through physical barriers, inflammatory responses, and phagocytic cells, and adaptive immunity, which generates specific targeted responses through B cell production of immunoglobulins (IgG, IgM, IgA, IgE) and T cell-mediated cellular immunity involving helper and cytotoxic lymphocytes. Understanding the developmental progression of pediatric immunity from fetal development through early childhood is essential, particularly the role of transplacental maternal antibody transfer that confers temporary protection and the physiologic immunoglobulin gap that follows. The chapter extensively covers pediatric HIV infection, including retroviral pathophysiology, mother-to-child transmission pathways, and the accelerated clinical progression characteristic of infected infants. Diagnostic approaches are differentiated based on age, with virologic testing such as DNA polymerase chain reaction required for children under 18 months whose persistent maternal antibodies prevent reliable serologic diagnosis. Treatment emphasizes aggressive combination antiretroviral regimens paired with prophylactic agents against opportunistic pathogens like Pneumocystis jiroveci pneumonia, alongside critical psychosocial considerations surrounding medication disclosure and adherence. The chapter addresses chronic immunosuppression from prolonged corticosteroid use, highlighting complications including adrenal insufficiency, linear growth impairment, and appropriate therapeutic tapering protocols. Autoimmune manifestations are illustrated through systemic lupus erythematosus, detailing multisystem inflammation, cutaneous presentations, and immunosuppressive pharmacotherapy combined with photoprotection strategies. Type I hypersensitivity reactions and anaphylaxis receive focused attention, covering immediate recognition, emergency epinephrine administration, and comprehensive allergen avoidance and management strategies applicable across school and community environments.