A quantitative method for measuring in vitro synthesis of IgA and IgG by human rectal mucosa: studies on normal controls and patients with hypogammaglobulinaemia.

A quantitative technique has been developed for measurement of immunoglobulin production by human rectal mucosa in vitro. The technique overcomes the problem of serum proteins trapped in the tissue by parallel measurements of Ig and human serum albumin (HSA) over a 6 day period. IgG, IgA, IgM and HSA were measured in supernatant fluids using sensitive radioimmunoassays. The technique has demonstrated IgG and IgA synthesis by rectal mucosa in vitro. The conclusion that the observed IgA and IgG was synthesized in vitro was supported by the demonstration that the production could be increased by pokeweed mitogen and blocked by emetine. This culture system has been applied to measure Ig synthesis by the rectal mucosa of immunodeficient patients.