The origins of the immunoglobulins in the mucous secretions of cattle

Abstract

The predominating immunoglobulin in the mucous secretions of cattle appears to be IgG1. Radioactive tracer studies using ¹³¹I-labelled IgG1 and ¹²⁵I-labelled IgG2 suggest that the larger part of this immunoglobulin is not derived from the plasma but is locally synthesized. Immunofluorescence studies indicate that this immunoglobulin is produced by lymphoid cells which can be observed in the lamina propria and at the base of the villi in the mucosae of the gut and respiratory system. There appears to be some degree of selectivity of transport of IgG1 from the plasma compared with IgG2, although this varies with the tissues.