Table 1.
Subject | Age IAA-positive (years)* | IAA affinity (l/mol) | IAA titre (units) | HLA DRB1/DQB1 genotype | Insulin B chain amino acids required for IAA binding | IAA binding to proinsulin | IAA binding to chicken insulin | IgA–IAA component |
---|---|---|---|---|---|---|---|---|
2 | 2·8–8·7 | 3·8 × 108 | 204·4 | 04,08/0302,0402 | B28, B29 | No | Yes | Yes |
6 | 1·8–7·5 | 2·2 × 108 | 20·8 | 04,16/not tested | B28, B29 | Yes | No | No |
3 | 9·4–11·0 | 3·5 × 105 | 108·0 | 01,07/0501,02 | B28, B29, B30 | No | Yes | Yes |
5 | 4·5–8·6 | 3·5 × 107 | 7·5 | 04,16/0302,0502 | B28, B29, B30 | No | No | Not tested |
7 | 2·6–3·1 | 2·0 × 107 | 34·6 | 14,16/0502,0503 | B28, B29 | No | No | No |
8 | 5·2–12·6 | 4·0 × 105 | 13·5 | 03,13/02,0603 | None identified | Yes | Yes | Yes |
The age range of positivity refers to that range in which samples were measured and tested positive. The earliest sample used for the competition analyses were the first positive sample for all the listed cases except subject 5 (age 5·6-year sample) and subject 8 (age 7·1-year sample). The titre and affinity in the table are for this sample. IgA: immunoglobulin A; HLA: human leucocyte antigen.