The aim of this study was to determine immunological factors associated with increased risk of mother-to-child transmission of HIV-1 that could be used as predictive markers in Tanzanian women. One hundred and thirty-eight HIV-1-seropositive and 117-seronegative mothers and their new-borns were recruited at delivery and followed up at Muhimbili Medical Centre in Dar es Salaam, Tanzania. Blood specimens from the mothers were analyzed for HIV-1 p24 antigen, p2-microglobulin (B2M), T-lymphocyte subsets, and presence of viral DNA in blood mononuclear cells by the polymerase chain reaction (PCR). Among 138 seropositive mothers, 30 (21.7%) had transmitted HIV-1 to their children, as shown by a positive PCR in the child. The vertical transmission rate was significantly higher in women with a percentage of CD4 lymphocytes ≤20 (eight of 24, 33%) or a level of B2M ≥2 mg/L (21 of 62, 34%) than in women with a higher percentage of CD4 lymphocytes (10 of 73, 14%) or a lower level of B2M (eight of 57, 14%) (p = 0.034 and 0.018, respectively). In eight of 18 (44%) transmitting mothers the percentage of CD4 lymphocytes was = ≤20, and in 21 of 29 (72%) transmitting mothers the B2M level was 3*2 mg/L. In women with both a low percentage of CD4 lymphocytes (≤20) and a high level of B2M (≥2 mg/L), the vertical transmission rate was 54%. Seven of 17 (41%) transmitting mothers had both a low level of CD4 lymphocytes and a high level of B2M. HIV-1 p24 antigenemia was significantly more common in transmitting than in nontransmitting mothers (four of 29, 14%, and two of 88, 2.3%, respectively; p = 0.05), but few mothers had this marker. We conclude that a low percentage of CD4 lymphocytes and a high level of B2M, especially when Dresent in combination, appear to be useful predictive markers for mother-to-child transmission of HIV-1 in Tanzanian women.
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