Administration of heterologous protein may be associated with serious allergic reactions. It would be of interest to examine the recommendations on skin testing in the use of available immunoglobulin products obtained from animal sources.

Package inserts for marketed heterologous immunoglobulin products were examined for information on the immunogenicity of the product, warnings, precautions, and recommendations on skin testing.

There are 8 polyclonal immunoglobulin products derived from equine, ovine, and rabbit sources, and 2 monoclonal antibody products of mouse origin. Three product labels state that skin testing should be performed prior to administration, and one strongly recommends it. One of the labels states that skin testing is not required, and another it is not suggested prior to dosing. In one case, the label stipulates that skin testing may be appropriate for high-risk individuals, while there is no mention of skin testing in the remaining three labels. These recommendations do not appear to correlate with the information on immunogenicity in the product labels. Moreover, there is no uniform description of what constitutes a “positive” skin test and when a product should be avoided should it occurs. Despite “negative” tests, some patients may still experience reactions to the products. Desensitization procedures are described in 3 labels. The above information is generally presented in the Warnings and/or Precautions sections, but one label gives it under the Indications and Usage section.

Current recommendations on skin testing for heterologous immunoglobulin products are varied. An evidence-based approach would be preferred in formulating such recommendations in the future.