QUANTITATIVE AND QUALITATIVE-ANALYSIS OF ANTITETANUS TOXOID ANTIBODY-RESPONSE IN THE ELDERLY - HUMORAL IMMUNE-RESPONSE ENHANCEMENT BY THYMOSTIMULIN

In order to explore the humoral primary and secondary response to teta nus toxoid (TT), and to define the possible immunopotentiating effect of the thymic hormone thymostimulin, we studied 13 elderly people, sel ected according to the Senieur Eurage protocol, vaccinated against TT, an antigen never encountered before. Six of them were treated with th ymostimulin before and during the immunization protocol. Specific anti -TT antibody level measurement and spectrotypic analysis were performe d on the sera collected from the subjects at different times over the immunization protocol. In addition, spontaneous in vitro production of anti-TT antibodies as well as cutaneous delayed hypersensitivity reac tions were also studied. Only one patient showed a detectable humoral immune response after the first immunization. After the booster, four of six thymostimulin-treated individuals, compared with only two of se ven controls, showed in vivo anti-TT humoral response; at the same tim e, spontaneous anti- TT production was detected in peripheral blood mo nonuclear cells from five of six thymostimulin-treated individuals but only three of seven untreated controls. These differences were highly significant (p < 0.0001). In addition, only in thymostimulin-treated subjects were the levels of serum anti- TT antibodies 14, 21 and 28 da ys after the booster significantly (p < 0.05) higher than the baseline values. The spectrotypic analysis of anti-TT antibodies performed by isoelectric focusing and reverse blotting showed total agreement with the' results from enzyme-linked immunosorbent assay. Cutaneous testing to recall antigens showed that among the thymostimulin-treated subjec ts four of six converted from negative to positive cutaneous reactions (only one to TT antigen). These four were also responders for anti-TT antibodies. In the control group, only one patient converted from cut aneous negativity to positivity for one antigen other than TT (p < 0.0 001). This observation suggests that the immunopotentiating effect of thymostimulin is via the T-helper network. In conclusion, this study d emonstrates the adjuvant effect of thymostimulin in the specific T-cel l dependent antibody response and emphasizes the necessity to consider a cycle of treatment with immunostimulants in elderly people undergoi ng specific vaccinations, and the importance of the search for biologi cal adjuvants in the construction of new vaccines.