82804
document
Immune response in healthy volunteers vaccinated with BCG plus killed leishmanial promastigotes : antibody responses to mycobacterial and leishmanial antigens . Antibody ( IgG ) responses to mycobacterial ( BCG ; PPD ; Mycobacterium leprae soluble antigen , MLSA ) and leishmanial ( Leishmania mexicana LV4 ) antigens were measured in 208 initially PPD and leishmanin skin-test negative volunteers divided into four vaccine groups as follows : 68 received BCG plus killed promastigotes ( group A ) , 47 received BCG alone ( group B ) , 47 received killed promastigotes alone ( group C ) , and 46 formed the diluent control ( placebo , group D ) . Three vaccine doses were administered at 8-12 week intervals . Vaccinees were bled immediately prior to each vaccination , and again at 3- and 12-month follow-up . Skin tests were performed prevaccination , and again at the 3- and 12-month follow-up . Anti-BCG , anti-PPD and anti-MLSA IgG levels increased significantly in groups A and B receiving BCG . The presence of leishmanial antigen ( with BCG ) in the inoculum suppressed the IgG response to Mycobacterium tuberculosis/Mycobacterium bovis-related ( PPD and BCG ) , but not M. leprae-related ( MLSA ) -related , antigens . A small but significant increase ( relative to prevaccination level ) in response to MLSA , but not to BCG or PPD was observed in the non-BCG-vaccinated groups . The background level of response to mycobacterial and leishmanial antigens was higher in the Venezuelan vaccinees than in non-endemic ( British ) volunteers . Responses to leishmanial antigen were not enhanced in the two vaccine groups receiving killed promastigotes ( with/without BCG ) compared with the BCG alone and placebo groups . Instead , all vaccine groups showed a pattern of response consistent with either ( i ) a response to the skin-test antigen or , more likely , ( ii ) seasonal endemic exposure to leishmanial antigen . Interestingly , this endemic response to leishmanial antigen was enhanced in the vaccine groups receiving BCG , despite the fact that group B received no leishmanial antigen in the vaccine inoculum . When prevaccination IgG levels ( mean + 3 standard deviations ) were used to determine a negative cut-off , a low percentage ( < 38 % ) of vaccinees converted to responder status for either anti-mycobacterial or anti-leishmanial responses , and those who did would be classified as 'low-responder ' status compared with titres observed in severe forms of disease . Hence , although there was evidence for a background endemic response to both leishmanial and mycobacterial antigens , there was no evidence that vaccination per se led to a potentially disease exacerbatory level of TH2-associated antibody response especially with respect to the anti-leishmanial response . ( ABSTRACT TRUNCATED AT 400 WORDS )
82805
Intervention_Pharmacological
BCG plus
82806
Intervention_Pharmacological
BCG plus killed promastigotes
82807
Intervention_Pharmacological
BCG alone
82808
Intervention_Pharmacological
promastigotes alone
82809
Intervention_Control
diluent control
82810
Outcome_Physical
Immune response
82811
Outcome_Other
Antibody ( IgG ) responses
82812
Outcome_Physical
Skin tests
82813
Outcome_Physical
leishmanial antigen
82814
Participant_Condition
healthy volunteers vaccinated with BCG plus killed leishmanial promastigotes
82815
Participant_Sample-size
208
82816
Participant_Sample-size
68
82817
Participant_Condition
Venezuelan vaccinees