EARLY PROGRESSION OF DISEASE IN HIV-INFECTED INFANTS WITH THYMUS DYSFUNCTION

Background Infants with congenital thymic deficiency (the DiGeorge syn drome) have immunodeficiency and a characteristic pattern of low CD4and CD8+ T-lymphocyte counts and low CD5+ B-lymphocyte counts. Because the thymus is essential for the generation of CD4+ cells, we sought e vidence of thymus dysfunction in infants infected perinatally with the human immunodeficiency virus (HIV). Methods We studied the immunophen otypes of 59 infants with maternally transmitted HIV, 5 infants with t he DiGeorge syndrome, and 168 infants exposed to HIV but not infected. The criteria for a presumed thymic defect were reductions in both the CD4+ and CD8+ T-cell subgroups during the first six months of life th at were confirmed in a subgroup of infants by low counts of CD4+CD45RA + and CD4+CD45RO+ T cells and CD5+ B cells. Results Of the 59 HIV-infe cted infants, 17 had immunophenotypes similar to those of infants with the DiGeorge syndrome. The risks of the acquired immunodeficiency syn drome (AIDS) by the ages of 12 and 24 months were, respectively, 75 pe rcent and 92 percent in these 17 infants, as compared with 14 and 34 p ercent in the other 42 infants (P<0.001). Nine of the HIV-infected inf ants with the DiGeorge-like immunophenotype (53 percent) died within s ix months of the progression to AIDS, as compared with only three of t he other infants (7 percent, P=0.006). Conclusions In some infants inf ected perinatally with HIV, a pattern of lymphocyte depletion develops that resembles the pattern in congenital thymic deficiency. Since HIV disease progresses rapidly in such infants, they may be candidates fo r early antiviral therapy and attempts at immune reconstitution. (C)19 96, Massachusetts Medical Society.