ANTHRAX POST-VACCINAL CELL-MEDIATED-IMMUNITY IN HUMANS - KINETICS PATTERN

Seven groups (2596 subjects) were vaccinated with a human live anthrax vaccine (HLAV) by three different routes (scarification, subcutaneous and aerosol). The vaccinees were tested for anthrax cell-mediated imm unity using the ''Anthraxin'' skin test at 7, 15, 30, 90, 180 and 365 days following vaccination. The kinetic pattern, obtained from all gro ups, shows a significant, five-phased curve: phase I (2-6 days post-va ccination) shows a slow increase in positive Anthraxin skin reactions. Phase II (7-15 days post-vaccination) shows an exponential rise to a maximum at day 15. Phase III (16-30 days post-vaccination) shows a dec rease to day 30. Phase IV (31-90 days post-vaccination) leads to a rel ative restoration of the positive skin reactions. During phase V (91-3 65 days post-vaccination) there is a continuous decrease in positive A nthraxin skin reactions. The loss of the skin test reaction on day 30 is a characteristic feature of post-vaccination anthrax cell-mediated immunity. It may be due to a blockade of macrophages by lethal anthrax toxin released by the multiplying vaccine strain. Epidemiological obs ervations of HLAV protective rates correlate with the phases of the sk in reaction kinetics. (C) 1997 Elsevier Science Ltd.