39 z - IgM zyxwv ANTI-HISTONE H-3 ANTIBODY ASSOCIATED WITH UNDIFFERENTIATED RHEUMATIC DISEASE SYNDROMES DANIEL P. MOLDEN, GARY L. KLIPPLE, CAROL L. PEEBLES, ROBERT L. RUBIN, ROBERT M. NAKAMURA, and ENG M. TAN A distinctive type of speckled antinuclear anti- body staining pattern was identified by indirect im- munofluorescenceon mouse kidney substrate in 4.8% of 5,976 specimens analyzed for antinuclear antibodies. This pattern, termed variable large speckles (VLS), consisted of 3-10 nuclear speckles ranging in size from approximately 0.2-2.0~. The pattern could be differen- tiated from other indirect immunofluorescence patterns related to specific antibodies. The predominant im- munoglobulin isotype demonstrating the VLS pattern zyxwv was IgM in 27 of 28 sera examined and IgG in 1 serum. VLS sera had substantial IgM antibodies to histone demonstrated by enzyme immunoassay , and further analysis of representative sera showed predominant antibody activity to histone class 3 (H-3). Adsorption with histone H-3 resulted in decrease or removal of antibody producing the VLS pattern. Available infor- matiofi showed that most patients with LgM antibodies of the VLS pattern had undifferentiated connective tissue disease symptoms. They were characterized by a heterogeneity of chronic symptoms including ar- thralgias, myalgias, inflammatory polyarthritis, myo- Publication number 3680BCR from the Research Institute of Scripps Clinic, La Jolla, California. From the W. M. Keck Foundation, Autoimmune Disease Center, Department zyxwvutsrq of Basic and Clinical Research, Scripps Clinic and Research Foundation, La Jolla, California. Supported in part by NIH grants AM-32063, AM-34358, and AI-10386. Daniel P. Molden, MD: Clinical Fellow; Gary L. Klipple, MI): Clinical Fellow; Carol L. Peebles, MS: Research Technician; Robert L. Rubin, PhD: Assistant Member; Robert M. Nakamura, MI): Member; Eng M. Tan, MD: Member. Address reprint requests to Eng M. Tan, MD, Department of Basic and Clinical Research, Scripps Clinic and Research Foun- dation, 10666 North Torrey Pines Road, La Jolla, CA 92037. Submitted for publication February 11, 1985; accepted in revised form June 14, 1985. - sitis, sicca symptoms, and pleurisy associated with ele- vation of the erythrocyte sedimentation rate. It remains to be determined whether the IgM anti-histone H-3 profile of these patients is a transient or long-standing serologic characteristic. The indirect immunofluorescence technique is a widely used method of screening for the presence of antinuclear antibodies (ANA). The patterns of nuclear fluorescence observed with this assay are indicative, but not diagnostic, of a specific type of antibody (1). There are many ANAs which display a variety of speckled staining patterns; among these are antibodies to Sm, RNP, SS-A (Ro), and SS-B (La). A speckled pattern which can be distinguished from others is that of the antibody to centromere/kinetochore (2). We report here another distinctive type of speckled pat- tern which is different from other speckled patterns and was first observed when mouse kidney sections were used as the substrate for the indirect immunoflu- orescence test. It consists of 3-10 distinct, variably shaped, 0.2-2.0~ nuclear speckles and will be referred to as the variable large speckled (VLS) antinuclear antibody pattern. Our studies provide information on the frequency, the clinical significance, the substrate, and the immune specificity of the VLS pattern. PATIENTS AND METHODS Patient sera. Of the 5,976 sera sent to this laboratory for routine ANA testing, using mouse kidney sections as substrate, 289 (4.8%) were observed to have multiple, vari- ably sized fluorescent nuclear speckles. They were classified as having a “variable speckled” ANA pattern. Titration data were available on 210 of these 289 sera, and 81 of the 210 Arthritis and Rheumatism, Vol. 29, No. 1 (January 1986)