2026 14 Immunology for the paediatrician

An understanding of basic immunology is essential in paediatrics. To know the normal development of the immune system in the early years, the components of the immune system, the concepts of innate and acquired immunity, of humeral (antibody) and cellular (T-cell) immunity, the role of phagocytes and complement. Secondary causes of immune dysfunction are common - post-sepsis, nephrotic syndrome, post-measles, protein losing enteropathy, splenic dysfunction. Primary immune deficiencies can be problems with any component of the immune system, and are generally rarer than secondary immune dysfunction (except selective IgA deficiency, which often presents with recurrent respiratory or gastrointestinal virus infection). Children with severe primary immune deficiencies present with recurrent infections of the respiratory and gastrointestinal systems, repeated soft tissue infections, sinusitis, bronchiectasis, and opportunistic infections such as CMV, pneumocystis, fungal and mycobacterial. The pattern of infections is a guide to the type of immune dysfunction. We discuss the basic and more advanced work-up for children with suspected immune deficiency.