In Vitro Proliferation of Lymphocytes from Human Volunteers ...

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In Vitro Proliferation of Lymphocytes from Human Volunteers ...

34^ International Journal of Leprosy^ 1987duration of immunity brought about by avaccine is crucial to its success, this is animportant advantage offered by the LTT. Itwould appear, therefore, that the results ofthe two assays would facilitate a better judgmentof the performance of the vaccine.This study shows that individuals vaccinatedwith 1.5 x 108 and 5 x 108 killedarmadillo-derived M. leprae develop astrong response to M. leprae antigens in theLTT 3 months after vaccination. The responseappears to remain high during theperiod of study (6 months-1 year). Furthermore,the in vitro response to M. lepraeantigens parallels the in vivo skin-test responseto these antigens in that both vaccinatedgroups showed a marked increasein response to M. leprae antigens after vaccination.The in vitro and in vivo responses to PPD,however, did not follow a parallel trend.While there was very little change in theskin-test responses before and after vaccination,the LTT response to PPD increasedsomewhat after vaccination. The reasons forthis divergence in trends and for the boostingeffect in the LTT to PPD are not altogetherapparent. One possible explanationfor the divergence is that the two assays donot measure identical phenomena. Insofaras the boosting is concerned, it is importantto ascertain whether the boosting is specificor nonspecific in nature. Because PPD, BCG,and Al. leprae are crossreactive (6), the effectmay be specific. However, the slight boostingof LTT responses to SK-SD, tetanustoxoid and diphtheria toxoid may indicatea nonspecific effect. It is also quite conceivablethat the boosting of the LTT responseto PPD may be a result of both specific andnonspecific effects.In conclusion, the results presented heresupport and extend the skin-test results reportedpreviously from the same group ofhealthy volunteers vaccinated with killed Al.leprae. Thus, it appears that in man, too,M. leprae is a potent inducer of cell-mediatedresponsiveness as assessed both invivo and in vitro. This responsiveness is ofconsiderable duration, remaining high up to1 year after vaccination.SUMMARYA killed, armadillo-derived Mycobacteriumleprae vaccine was examined for itsability to induce cell-mediated responsivenessin purified protein derivative (PPD)-positive volunteers residing in a nonendemiccountry using the lymphocyte transformationtest (LTT). A marked increase in theproliferative responses to a M. leprae-solubleantigen preparation was observed inthe two groups which were vaccinated withthe highest doses of the vaccine, i.e., 1.5 x108 and 5 x 108 bacilli. This increase wasobserved in both groups 3 months after vaccination,and persisted for the study periodof 1 year. The in vitro proliferative responsesto whole bacilli, of both armadilloand human origin, showed a similar butsmaller increase 3 months after vaccination.Some enhancement of responses to crossreactiveantigens, such as PPD, and tounrelated antigens such as streptokinasestreptodornase,tetanus toxoid and diphtheriatoxoid, was also observed. Thus, theLIT revealed that while the killed M. lepraevaccine induced a specific cell-mediated responseto Al. leprae, it was also responsiblefor a nonspecific immune-enhancement effectin healthy volunteers.RESUMENUsando la prueba de transformaciOn de linfocitos(PTL) se probO una vacuna muerta de Mycobacteriumleprae derivada de armadillo en cuanto a su capacidadpara inducir respuestas inmunes celulares en voluntariosPPD-positivos residentes de on pais no endemic°.En los 2 grupos que fucron vacunados con lasdosis mns altas de la vacuna (1.5 x 10 y 5 x 10'bacilos) se observO un marcado increment° en las respuestasproliferativas contra una preparaciOn antigenicasoluble derivada del A/. leprae. Este increment°se observO en ambos grupos 3 meses despuês de lavacunaciOn y persistiO durante el period() de estudiode 1 alio. Las respuestas proliferativas in vitro contralos bacilos totales tanto de armadillo como de humanos,mostraron on increment° similar pero más pequa°3 meses despuês de la vacunaciOn. Tambiên seobservO cierto increment° de las respuestas contraantigenos de racciOn cruzada (PPD) y contra antigenosno relacionados (estreptoquinasa-estreptodornasa, toxoidetethnico y toxoide difterico). Asi, la l'TL revelOque mientras la vacuna de M. leprae muerto indujouna respuesta celular contra Al. leprae, tambiên foeresponsable de on elect° incrementador no especificode la respuesta inmune en los voluntarios sanos.RÈSUMÈOn a utilisê rêpreuve de transformation lymphocytaire(LTT) pour examiner dans quelle mesure on

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