Impaired humoral immunity in PNG Highlanders

Immunological function was investigated in 42 adult Papua New Guinea villagers and 38 adult males who had been inmates of the Goroka prison for more than three months. Serum IgG, IgA, IgM and IgE levels were all significantly elevated in both Papua New Guinea groups when compared to Australians. Antibody responses to tetanus toxoid immunization were greatly impaired in both Papua New Guinea (PNG) groups. The impairment was greater in the villagers. Antibody responses to immunization with typhoid vaccine were also impaired in both P.N.G. groups compared with Australians. Some evidence was obtained to indicate that unresponsiveness was associated with lower serum albumin levels, suggesting a relationship to protein deprivation. Antibody response after first immunization was predominantly in the IgM class for both tetanus and typhoid vaccines, with conversion to the IgG class on re-immunization. This indicates that most P.N.G. highlanders have not been exposed to these antigens previously. The prevalence of autoantibodies (mitochondrial, gastric parietal cell and antinuclear) was similar to that of a normal Australian population. The prevalence of smooth muscle antibodies, although higher, was probably not remarkable. Australia antigen was found in 9%, compared with less than half of 1% in the Australian population. Cellular immune function, as measured by delayed hypersensitivity reactions, was not impaired. The implications of these findings for mass immunization programmes are discussed.