BETA-2-MICROGLOBULIN LEVELS IN DRUG-USERS - THE INFLUENCE OF RISK BEHAVIOR

Beta-2-microglobulin (beta-2M) levels were measured in 217 Edinburgh drug users to assess their usefulness as a marker for HIV-related disease. Eighty HIV-seronegative drug injectors had significantly higher levels than 100 HIV-seronegative blood-donor controls. Amongst 137 asymptomatic HIV-seropositive drug users, those who were defined as continued drug users had significantly higher beta-2M levels and percentages of CD3+ T lymphocytes with DR Class II expression than non-injecting drug users. Beta-2M levels correlated with the percentage of activated DR+ CD3+ T lymphocytes. These findings indicate that changes in beta-2M levels may reflect differences in drug-injecting behaviour and are not influenced solely by HIV status or progression. These changes in beta-2M probably represent differing degrees of immunostimulation resulting from the antigenic challenges afforded by continued or frequent drug injection. It is important to establish normal ranges for beta-2M from HIV-seronegative controls who are matched with respect to risk group and behaviour. All these factors should be taken into account if beta-2M is to be used as a marker of HIV progression.