Measurement of total, monomeric and polymeric IgA in human faeces by electroimmunodiffusion

Total (t), monomeric (m) and polymeric (p) immunoglobulin A (IgA) levels were simultaneously measured in mixed faecal material collected over three consecutive days using a modified one-dimensional immunoelectrophoretic assay, which is a precise and reproducible method. Faecal t-, m- and p-IgA levels were statistically higher in 32 diarrhoeic patients than in a group of 16 healthy subjects (respectively 2.2, 2.6 and 2.0 times the normal). The values were also significantly different (P less than 0.001) when results were expressed as output per day in order to estimate the secreting capacity of gut. Moreover, the m-IgA/t-IgA percentages were significantly higher in faeces from diarrhoeic patients (42.3%) than in normal faeces (26.5%). These results confirm the importance of faecal IgA determination in estimating the local production of the IgA in various gastrointestinal tract disorders.