Pesquisa de anticorpos antitoxina diftérica e fenotipagem de linfócitos T em indivíduos soronegativos e soropositivos para o HIV-1 acompanhados no Instituto de Biologia do Exército Rio de Janeiro

Abstract

Serologic data on diseases that are preventable by vaccine are useful to evaluate the success of immunization programs and to identify susceptible subgroups. In the last 20 years the childhood immunization program has been efficient in the control of the diphtheria in many countries. However, an important rate of adult population remains susceptible to the illness, since diphtheria protective antibodies decline with time. HIV-1 infection leads to a progressive loss of immune functions. With the increase of life expectancy of HIV-1 patients, and also the increment of infections, it is important to known the antibody levels to diphtheria toxin in these population. The aim of this study was to evaluate the IgG levels to diphtheria toxin and T lymphocytes (LT) counts in HIV-1 infected and non- infected individuals assisted at the Instituto de Biologia do Exército (IBEx), Rio de Janeiro. We investigated the correlation between specific antibody levels and the following parameters of the study groups: gender, age-group, military or civilian origin, previous diphtheria immunization, CD4+ and CD8+ counts. For HIV-1 patients, we also analysed the correlation of specific antibodies with viral load and the use of highly active antiretroviral therapy HAART. A commercial diphtheria-ELISA kit (IBL Immuno-Biological Laboratories, Hamburg, Alemanha) was used to evaluate IgG levels in serum samples of 180 individuals. Blood donors accounted for 75 individuals and 105 subjects were HIV-1 patients. About 60% of individuals were partially protected against diphtheria (specific IgG levels &#8805; 0,1 < 1,0 IU/mL). About 56% of blood donors were protected against diphtheria (specific IgG > 1.0 IU/mL). Howerver, only 29% of HIV-1 patients showed the same level of protective antibodies. For the civilian blood donors, there were no correlation between specific antibody levels and age group. In contrast, a negative correlation was observed in the military group. There were no differences in diphtheria serology according to CD4+ counts of HIV-1 patients or blood donors. Interesting, HAART- treated (n = 84) patients showed a significantly lower antibody response (geomean of 0.39 IU/mL) than untreated patients (geomean of 0.58 IU/mL, n = 19). As tetanus and diphtheria antibodies tend to decrease with time, the difference in age between HAART-treated patients (mean of 46 years) and those not being treated (mean of 35 years) might introduce a bias in the study. Concluding, the existence of susceptible military and civilian adults in our community, including HIV-1 patients, reinforce that reliable seroepidemiological data and immunization campaigns should be routinely stimulated.