The effect of
HIV infection on immune response to
diphtheria and
tetanus primary immunisation was investigated in 24 HIV-1-positive multi-transfused (MT) children with thalassaemia and compared with 48 HIV-1-negative MT thalassaemic children and 36 HIV-1-negative non-transfused (NT) children in the community.
Diphtheria and
tetanus antibody levels in the HIV-1-positive MT group were comparable with the two HIV-negative groups. The proportions of children with antibody titres below the protective level (i.e. <0.01 IU/ml) for antidiphtheria
antibodies were 20.8, 16.6 and 16.6%, and 12.5, 12.5 and 13.9% for anti-
tetanus antibodies in the three groups, respectively. On the other hand, delayed-type
hypersensitivity (DTH) response to
diphtheria and
tetanus antigens was significantly depressed in the HIV-1-positive group compared with the HIV-negative controls. The mean percentages of both mature (CD20+) and immature (CD10+) B-cell counts were significantly higher in the HIV-1-positive group than in the HIV-negative MT and NT groups (p<0.05). Levels of serum
immunoglobulins and spontaneously secreted
immunoglobulins were significantly higher in the HIV-1-positive group compared with both HIV-negative groups. The HIV-1-positive group showed a mean (SD)
IL-6 of 52.9 (28.8) pg/ml compared with 23.7 (12.1) pg/ml and a detection rate of 54.2% in the HIV-negative MT group, and 23.6 (8.2) pg/ml and a 50% detection rate in the HIV-negative NT group. The
IL-2 level was significantly lower (p<0.05) in the HIV-1-positive group [41.7% detection rate and mean (SD) 28.8 (17.1) pg/ml] than in the HIV-negative MT and NT groups [75% and 83.3% detection rates and mean (SD) 57.2 (42.3) pg/ml and 99.3 (51.1) pg/ml, respectively]. During follow-up for 3 years, the frequency of major
infections was significantly higher in the HIV-1-positive group than in the other two groups. Acute
pneumonia and acute
sinusitis were the predominant
infections regardless of HIV status while primary bacteraemia,
osteomyelitis, pyogenic
meningitis and
septic arthritis were common in the HIV-1-positive group. We conclude that, in HIV-1-infected children pre-immunised with DPT, DTH response to
diphtheria and
tetanus antigens might be more reliable than anti-
diphtheria and anti-
tetanus antibody levels in predicting susceptibility to major
bacterial infections.