O-glycosylation of salivary IgA as determined by lectin analysis.

Coldharbour Lane, London SE5 9NU Jacalin MPA PNA DBA 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 In humans two types of immunoglobulin alpha (IgA) exist which differ in terms of their glycosylation on the a heavy chain: IgA 1 has two N-linked glycans and 5 0-glycans per heavy chain, IgA2 has 4-5 N-glycans but no 0-glycans per heavy chain [ 11. It appears that the glycosylation of IgA may vary depending on the tissue source. For example the 0-glycosylation of IgAl from milk [ 21 and serum [ 31 has been analysed in separate studies and found to differ in degree of sialylation. It may be that the glycosylation of IgA differs between individuals. Studies were thus undertaken to analyse the 0-glycans of IgAl from parotid saliva. Previously purification of IgA from parotid saliva has often involved long and complicated protocols including acid precipitation which can oxidize carbohydrates, particularly sialic acid. Gel filtration of parotid saliva provided a novel one step purification of secretory IgA that did not affect any carbohydrates present.