Children under 13 years of age are the fastest growing sub-group of HIV-infected persons today. The course of HIV-1 infection in this age group differs from that in adults: the cardiac and pulmonary complications are far more aggressive. The NHLBI has several programs that deal with HIV infection in this age group.

P. carnii pneumonia and lymphoid interstitial pneumonia are major problems affecting infants and children infected with HIV. These disorders have not been adequately investigated and a large number of questions remain unanswered. Frequent cardiovascular abnormalities have also been found in patients infected with HIV, but the incidence and etiology of these abnormalities in the population of infants and children, infected in utero and perinatally, have not been delineated. An NHLBI program supports investigation of the pathogenesis of these disorders, along with their natural history. It was started in 1989, and 800 infants and children are being studied 49 percent of whom are black and 33 percent of whom are Hispanic.

A study to examine the effect of immune globulin on HIV-1 transmission from the infected mother to the fetus was started in fiscal year 1993. The initial safety and pharmacokinetic data has been collected and the efficacy portion of the trial is now in progress.

A study to evaluate the efficacy of HIVIG in treating HIV-1 infection in infants and children will is currently recruiting patients. Results are expected within the next year.

NHLBI-supported investigators are studying the natural history of transfusion-transmitted HIV-1 infection in children with congenital anemias or with coagulation disorders. About 173 children have been studied to date, and the findings include: children 1-7 years had leukocyte counts and percentages of granulocytes, monocytes, natural killer cells, and T-cell markers that were significantly higher than for control children. Percent total lymphocytes were decreased for this age but total number of lymphocytes and T- and B-cell counts were similar to controls. Platelets were not increased. Adolescents (8-17 years) and adults (< 18 years) had total leukocytes and monocytes that were increased, and lymphocyte counts that remained level instead of decreasing as did comparably aged controls. Lymphocyte subsets typically increased in count, but their percentage remained similar to children.

This program, which started in fiscal year 1994, is supporting investigation of the non-infectious pulmonary complications of HIV. One such disorder, lymphoid interstitial pneumocystis occurs primarily in infants with HIV. This study will end in 1999.

The NHLBI is co-funding a study with the Pediatric AIDS Foundation to produce genetically altered human hematopoietic stem cells which are resistant to HIV infection. Such a stem cell could be used therapeutically in an attempt to immunologically reconstitute an infected infant.