TO MANUFACTURERS OF REAGENTS FOR FLUOROCHROME-LABELLED ANTIBODY TESTS

1OMANUFACTURERS OF REAGENTS FOR FLUOROCHROME-LABELLED ANTIBODY TESTS The World Health Organization and the Standardization Committee of the Interna- tional Union of Immunological Societies (IUIS) intend to make available a standard fluorochrome-labelled antihuman IgM conjugate to the specifications indicated below. Tenders for the contract for the preparation of the required 4 000 ampoules, each containing 0.25 ml of conjugate, should be submitted together with 10 representative samples of the material offered, in order that it may be assessed for suitability by the Immunofluorescence Sub-committee of the IUIS Standardization Committee. The date by which tenders and samples should be submitted has been extended to 30 September 1975. They should be sent to: International Union of Immunological Societies Standardization Secretariat c/o Dr G. Torrigiani Immunology World Health Organization 1211 Geneva 27 Switzerland R. Ritts G. Torrigiani IUIS WHO ANTI-IgM CONJUGATE SPECIFICATIONS 1. Specificity 1.1 The conjugate must be class-specific for human IgM in the definitive FLA tests for, e.g., syphilis, toxoplasmosis, and rubella. 1.2 It must not react with other immunoglobulin classes, light chains, or complement components, and it must not exhibit other inappropriate reactions in the definitive FLA test systems. 1.3 It must be free from immune complexes and all other human serum components. 1.4 Insolubilized absorbents should be used. 2. Potency 2.1 The conjugate must have a plateau titre of at least 1/8 in a congenital-syphilis system. 2.2 It must not show nonspecific staining at a concentration of less than 4 times the end-point titre. 3. Immunogen Purified IgM from a pool of monoclonal sera or from normal human sera. 4. Filling andfreeze-drying This should be done according to the recommendations contained in document WHO/BS/773/65, pages 7-12. 5. Adequate stability data must be provided. 6. The following information on the material should be provided, as laid down at the meeting on Standardization of Immunofluorescence, held in London in 1968, and by the MRC working party (see Immunology, vol. 20, No. 1 (1971)): 6.1 Name and address of the manufacturer. 6.2 Proper name of the product and its batch or lot number. 6.3 Manufacturer's recommended expiry date. 6.4 Type of fluorochrome used to label the antibodies. 6.5 (a) If a standard is available, the potency in relation to that of the standard, or (b) If a standard is not available, the intended working dilution (with range), as found in a specified test. 6.6 Ratio of "optical densities" (i.e., absorbance values) before the addition of any stabilizers. 6.7 Any special information about processing, including additions and absorptions. 6.8 Any known cross-reactivity, especially to immunoglobulin of other species. 6.9 Type and concentration of preservative used, if any.