| Abstract: | Persons with antibody to hepatitis B surface antigen (anti-HBs) activity in their serum that is entirely immunoglobulin M (IgM) in nature appear not to be protected against hepatitis B virus infection. Because commercially available anti-HBs kits do not distinguish between IgM and immunoglobulin G anti-HBs activity, the question of whether or not to immunize high-risk persons with anti-HBs alone has recently been the subject of much controversy. The present study in Calgary and Winnipeg, 1984-1985, documents the nature of anti-HBs activity in sera from three groups of "high-risk" persons. Group I consisted of 26 health care employees positive for anti-HBs but negative for other hepatitis B serologic markers. Group II consisted of 26 members of high-risk ethnic populations who were also positive for anti-HBs alone. Group III consisted of 29 persons from both populations (16 health care workers and 13 members of high-risk ethnic populations) positive for both anti-HBs and antibody to hepatitis B core antigen (anti-HBc). The majority of persons in groups I and II (58% and 50%, respectively) had low levels of anti-HBs activity (sample/negative control ratio (ratio unit) less than 10), as compared with only three of group III (p less than 0.00001 and 0.0001, respectively). Of the remaining persons with presumably protective levels of anti-HBs (ratio unit greater than or equal to 10), treatment with 0.2 mM dithiothreitol, an agent that completely destroys IgM immunoglobulin activity, resulted in less inhibition of anti-HBs activity in sera from groups I and II (48.2 +/- 31.1 and 51.9 +/- 19.5, mean +/- standard deviation, respectively) than group III sera (69.9 +/- 22.0) (p less than 0.05). In no case was anti-HBs activity completely eliminated following dithiothreitol treatment. The results of this study indicate that anti-HBs activity in the majority of high-risk persons with presumably protective levels of anti-HBs is not exclusively IgM in nature. |
