Phytohemagglutinin mitogenic response of normal individuals vaccinated with hepatitis B vaccine

The phytohemagglutinin (PHA) blastogenic response of normal healthy individuals was studied before and after vaccination with hepatitis B surface antigen. The PHA response was suppressed 2 d after the first dose of vaccine but was not affected by the second and the third doses of vaccine. The suppressed PHA blastogenic response on day 7 was not enhanced by the addition of interleukin-2 or indomethacin even though an increase in cell number expressing CD25 was observed. The removal of CD4+ or CD8+ cells enhanced the PHA response but only on days 2 or 4 and not at other sampling times, which suggests that the suppression is mediated by CD4+ or CD8+ cells. The addition of interleukin-2 alone or with PHA did not reverse the suppression at any time tested. In vitro induction of suppressor cells was performed and was blocked by the addition of indomethacin at the time of culture initiation.