The evolving population of immunocompromised children.

The immunocompromised host was first defined around the host abnormalities and consequent infections that were associated with congenitally acquired deficiencies. Although the impact of the deficiency on the affected child was considerable, the numbers of such children remained small. With the advent of immunosuppressive therapy and cytotoxic regimens for the effective treatment of cancers and autoimmune diseases, an increasingly larger number of children became immunocompromised and thus subject to serious infectious complications. More recently a new population of immunocompromised children have emerged, those infected with the human immunodeficiency virus; over the next several years this group of patients threatens to become the predominant group of "immunocompromised hosts" in pediatrics. Regardless of whether the immunodeficiency is a genetically transmitted immunodeficiency or results from cytotoxic therapy or from infection with human immunodeficiency virus, the incidence and pattern of the infections that occur parallel the targets of the immune system that are adversely affected or destroyed. In some cases, this may represent only a single component of the immune system whereas in others, multiple aspects of the immune matrix have been altered or perturbed. Two goals apply to the management of the immunocompromised child: (1) to identify the basis for the immunodeficiency and to develop methods to restore or replenish it; (2) to define the spectrum of infectious complications that can occur in association with the immunocompromised state and to develop regimens to treat or prevent them, at least until the underlying defects can be dealt with in a more definitive manner.(ABSTRACT TRUNCATED AT 250 WORDS)