In 1956, Gitlin and Janeway published their classic report, "Agammaglobulinemia: Congenital, Acquired and Transient Forms" . This was the first clinical description of transient form of hypogammaglobulinemia of infancy (THI). Despite this discovery decades ago and the significant progress in understanding the pathogenesis of other forms of humoral immunodeficiency, very little is known about THI.
Clinicians must have the appropriate tools to accurately diagnose THI and the ability to distinguish the disorder from other types of immunodeficiency. Early accurate diagnosis and effective treatment may prevent devastating consequences.
This topic review summarizes the characteristics of THI, including definition, possible etiology(ies), clinical manifestations, treatment, and prognosis. An overview of primary humoral deficiencies is presented separately. (See "Primary humoral immune deficiencies: An overview".)
IMMUNOGLOBULIN LEVELS IN INFANCY
Serum immunoglobulin levels in infancy vary based upon the maturity of the newborn, placental transfer of maternal immunoglobulin, time since birth, and ability of the infant to produce immunoglobulin (table 1 and figure 1).
Immunoglobulin G — At birth, most serum immunoglobulin G (IgG) is derived from the transfer of maternal IgG across the placenta during the third trimester of pregnancy. As a result, serum IgG levels at birth are commonly equal to or slightly higher than maternal serum IgG levels , and premature infants have lower IgG concentrations than full-term infants. Premature infants of 30 to 32 weeks' gestation have cord IgG concentrations of approximately 400 mg/dL . Small for gestational age (SGA) neonates may also have somewhat lower IgG levels than full-term neonates, reflecting possible impaired placental transport [4,5].