A high proportion of sera of heroin addicts possesses anti-HLA class I and class II reactivity

Naturally occurring IgG anti-HLA alloantibody does not correlate with HIV type 1 resistance in Nairobi prostitutes

In an effort to identify an immunological basis for natural resistance to HIV-1 infection, we have examined serum antibody responses to HLA class I antigens in female prostitutes of the Nairobi Sex Workers Study. Anti-HLA antibodies are known to block HIV infectivity in vitro and can be protective against SIV challenge in macaques immunized with purified class I HLA. Thus, it was postulated that broadly cross-reactive alloantibodies recognizing common HLA alleles in the client population might contribute to the prevention of heterosexual transmission of HIV. In fact, 12% of the women were found to have serum IgG antibodies against class I alloantigens. However, this alloantibody did not correlate with the HIV status of the women and was found in a similar proportion of HIV-positive and HIV-resistant women. The observed levels of alloantibody did not increase with HIV infection in susceptible individuals, suggesting that potential antigenic mimicry between HIV and host HLA class I antigens does not significantly increase levels of anti-class I antibodies. The lack of correlation between serum anti-allo-class I HLA antibodies and the risk of sexual transmission indicates that this humoral immune response is unlikely to be the natural mechanism behind the HIV-resistance phenotype of persistently HIV-seronegative women. This result, however, does not preclude the further investigation of alloimmunization as an artificial HIV immunization strategy.

Human immune toxicity

This review examines xenobiotic toxicity to the immune system, stressing in particular those aspects of most relevance to humans. Immunotoxicity is examined especially from three points of view: by what immunological component is affected, by classes of foreign agents that adversely affect the human immune system and by critical evaluation of human case reports and epidemics. Mechanisms by which xenobiotics interrupt cytokine networks are emphasized. The concept that microbial agents, both environmental as well as infectious, may act as immunotoxicants, either alone or in synergism with conventional agents is introduced. Instances of human immunotoxicology are critically evaluated in terms of clinical relevance, i.e. whether increased susceptibility to opportunistic infections or tumor emergence takes place in the affected individuals.

In vitro immunotoxicology and immunopharmacology: studies on drugs of abuse

The application of immunotoxicology to the toxicologic assessment of drugs of abuse is a field of increasing importance. Interest in the effects of drugs of abuse on the immune system has greatly increased as a result of the AIDS epidemic. If drugs of abuse compromise the immune system, their use may well become a predisposing factor in the development or enhancement of AIDS in high-risk groups. Therefore development and validation of newer methods of assessment of immunotoxicology and their adaptation to routine analysis is an absolute necessity. An important feature in toxicology in general, and in immunotoxicology in particular, is the need to develop in vitro assessment systems. Recent research has provided newer models, data on correlations of immune function variables, and a better understanding of the biologic relevance of certain immune function parameters. This paper analyzes these features in relation to the role of drugs of abuse in the modulation and alteration of the immune system and reviews the various in vitro techniques that could be used to evaluate immunotoxicity.