DEVELOPMENT OF IGG RESPONSES TO MYCOBACTERIAL ANTIGENS

Recent studies link mycobacterial and human heat shock protein antigen s with autoimmune diseases. Little is known about the development of a ntibody responses to these antigens in children. IgG responses to myco bacterial antigens were studied in children living in the UK (an envir onment low in mycobacteria) who had not received BCG vaccination. Age curves of IgG response to sonicates from different species of mycobact eria were similar suggesting that the greater part of the developing I gG response is to the common antigens shared by all mycobacteria. The major part of the IgG response was to carbohydrate antigens: lipoarabi nomannan is a mycobacterial cell wall carbohydrate and was confirmed a s a major immunodominant antigen. Infants showed a marked early respon se to the mycobacterial 65 kilodalton (kDa) and 70 kDa heat shock prot eins, but not to the human 65 kDa heat shock protein. The early IgG re sponse to heat shock proteins may reflect cross reactivity to proteins released by a wide variety of bacteria (possibly from breakdown in th e gut) or recognition of other immunodominant antigens with high level s of cross reactivity to self.