Basics in standardization and practical applications of immunofluorescent microscopy: standardization of antinuclear antibody tests.

Abstract

ANA tests are, at present, the primary example of the diagnostic use of an indirect IF method. Appropriately standardized and interpreted ANA tests afford the primary sero-diagnostic screening test for certain connective tissue diseases. In the present state of the art of ANA testing, it appears possible to achieve appropriate standardization in up to 70% of laboratories, however, further work remains to be done to achieve a 90% or higher frequency of reliable testing among clinical laboratories for a given antigenic substrate. The present indications for the preparation and use of this and other IF methods assay systems for clinical laboratory studies are as follows: a. For each antigen substrate used for ANA tests, the manufacturers of kits or the laboratories which prepare their own ANA test reagents, should take responsibility for assuring that the sensitivity of their test systems as measured by ANA titers falls in the range expected for that particular antigenic substrate. b. If adequate assurance of the appropriate sensitivity level of a given ANA test system is provided both by their manufacturers and users, then physicians should be supplied with data on the frequencies of biologic false positives for different age groups of males and females as well as frequencies of biologic false negatives for at least the major diseases for which ANA are of diagnostic significance. Part II of this report (Chorzelski et al., in press) presents data on this point. c. Since ANA tests detect a heterogeneous population of antibody specificities, several of which are now recognized as having distinct clinical significance (Tan, 1981), appropriately standardized tests for each of these diagnostically relevant antibodies to identified nuclear antigens needs to be made available to physicians by clinical laboratories. They need to be provided with data on the frequencies of false negatives, biologic false positives and, importantly, with data on the kinetics or dynamics of the relationships between demonstrable immune responses and the clinical manifestation of the diseases. Much of this remains to be done. d. Steps need to be taken toward standardization and evaluation of other immunofluorescent microscopic methods used in clinical laboratories, notably the tests for anti-smooth muscle antibodies (Doniack and Roitt, 1968), the anti-mitochondrial antibodies (Paronetto and Popper, 1976), antithyroid antibodies (Johnson et al., 1965), antibodies to epithelial antigens (Beutner et al., 1979; Beutner et al., 1970) and others, (Hekman, Rumke, 1976; Kaplan, 1976; Rose and Witebsky, 1968; Rule and Genkins, 1976).(ABSTRACT TRUNCATED AT 400 WORDS)