ANTI-HLA ALLOANTIBODY IS FOUND IN CHILDREN BUT DOES NOT CORRELATE WITH A LACK OF HIV TYPE-1 TRANSMISSION FROM INFECTED MOTHERS

Searching for mechanisms of natural resistance to HIV infection with w hich to guide HIV vaccine design, we have examined antibody responses to HLA class I antigens in children of HIV-infected mothers, Anti-HLA antibodies are known to block HIV infectivity in vitro and can be prot ective against SIV challenge in macaques immunized with purified class I HLA, It was hypothesized that alloantibody to maternal HLA in child ren might contribute to the prevention of mother-to-child transmission of HIV-1, In fact, a surprisingly high proportion of the children exa mined, 22%, were found to have antibody against class I alloantigens. This alloantibody, however, did not correlate with the HIV status of t he children and was found in a similar proportion of children of HIV-n egative mothers, The HLA specificity of the antibody was not correlate d with noninherited maternal HLA alleles and occurred with a higher fr equency in older children, This result suggests environmental factors, rather than exposure to maternal cells, are involved in the formation of the alloantibody, The finding that anti-allo-class I HLA antibodie s are not associated with a decreased risk of mother-to-child transmis sion indicates that this humoral immune response is unlikely to be the natural mechanism that accounts for the lack of transmission observed in many births, This result, however, does not preclude the further i nvestigation of cellular alloimmune responses, or the use of alloimmun ization as an artificial HIV immunization strategy.