IGE and IGD in Human Colostrum and Plasma

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Abstract
Summary: Using radioimmunoassay techniques, we measured IgE and IgD levels in paired colostrum and plasma samples obtained within 4 days postpartum. In colostrum, IgE was detected in concentrations of 0.5–6 IU/ml in 16 out of 39 samples (41%) and < 0.5 IU/ml in the remainder, whereas IgD was detected in all samples in concentrations of 2–2000 μg/dl. Only a moderate correlation was found between colostral and plasma levels of both IgE (r = + 0.60) and IgD (r = +0.74). The correlation coefficient between IgE and IgD in plasma was 0.23, whereas in colostrum it was only 0.05. The colostrum:plasma ratio of IgE varied strikingly from that of IgD; tbe ratio of IgD was 0.1–22.2 times that of IgE. The findings argue against passive transfer of IgE and IgD from the circulation to milk and suggest possible local mammary production of either or both of these two immunoglobulins. Speculation: In some patients, local production of IgE and/or IgD probably occurs in the mammary gland. One may hypothesize that previous antigenic exposure at other mucosal surfaces may not only determine the IgA antibody content of milk but also may influence the specificity of antibodies belonging to other immunoglobulin classes that appear in human milk. Whether the IgE and IgD antibodies in breast milk have similar specificities for antigens as the IgA antibodies in milk remains an interesting but unanswered question.