A radioimmunological method for assaying rheumatoid factor is proposed and analyzed. The method is based on the reaction between rheumatoid factor, either purified or present in serum, and purified labeled yG globulin. This assay permits a quantitative estimation of rheumatoid ONSIDERABLE EVIDENCE indicates that C rheumatoid factor (RF) consists of a group of antibodies of the yM globulin class directed against antigenic determinants present on the yG globulins and particularly on the Fc fragments.' Since these y G globulins are available in purified form2V3 and can be labeled with radioactive iodine, it is possible to perform a radioimmunological determination of RF similar to previous assays of insulin: growth h~r m o n e ,~-~ follicle-stimulating and luteinizing hormone,8-9 and other protein and polypeptide hormones.In our procedure, a standard curve was first prepared showing the percentage of labeled y G globulin which is bound by known, increasing amounts of isolated and purified RF.1° We then determined the percentage bound by the yM globulins in a specimen of rheumatoid arthritis serum capable of agglutinating sensitized latex particles. By referring this value to the standard curve, we were able to determine the RF content of the serum studied. Sera from normal subjects and from patients factor levels in rheumatoid-positive serum and provides evidence that rheumatoidnegative serum contains factors which can bind labeled YG globulin. Normal serum assayed by this method does not ordinarily contain such factors.with rheumatoid arthritis giving a negative latex test response were also evaluated. MATERIAL AND METHODSyG globulin. The preparation of y C globulin used was purified by M. Radermecker,:t utilizing a method similar to that of Peterson and Sober.2 Immunoelectrophoresis,~3 radioimmunoelectrophoresis,s and Sephadex G200 filtration established that the preparation consisted essentially of proteins of the yG globulin class and that no other type of protein contaminated it in quantities sufficient to be discernible by these methods. The yG was denatured by heating at 63OC for 10 min.Rheumatoid factor. The RF was isolated according to the method of Lospalluto and Ziff.11 Protein concentration was determined by UV spectrophotometry (280 p ) using Cohn fraction I1 as reference.Rheumatoid arthritis serum. Forty specimens of serum from patients with rheumatoid arthritis were studied. Twenty-six contained RF as indicated by their agglutination of latex particles coated with Cohn fraction 11; the remaining 14 were negative by this test.Normal serum. Sera from 12 normal subjects, ages 18-46, were assayed.LabeZing of yG globulin. Ten nanograms of yG globulin were labeled with 2.5 mC 1311 by the method of Greenwood et a1.12 The labeled yG

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Two types of laser diodes (LD) based equipment for rheumatology are introduced. The first is a portable device which contains a single LD emitting at 890 am laser pulses (time full width 100 nsec ) of reprate tunable within ( 0.5 -1.5 ) kHz; the laser beam average power is 0.7 mW at 1 kHz reprate. The second is computer controlled, contains one HeNe laser and 5 LD allowing 6 modes of patients irradiation (PLACEBO effect evaluation included ). HeNe laser works in cw at 632.8 am; LD work each as described for the portable equipment. HeNe and LD beams are superposed so that HeNe laser spot in the irradiation plane has 60 mm diameter and the LD spots cover a 50 mm diameter disc centered on HeNe laser spot.Clinical applications using the second type ofequipment are reported; 1287 patients were treated between October 1991 and October 1994. Female/male ratio was 4: 1 and their age distribution was between 18 and 85 years. The average number of exposures was 1 0 and the mean exposure time was 7 minutes.Studies were made on the treatment of rheumatoid arthritis, seronegative arthritis, degenerative joint diseases, abarticular rheumatism, osteoporosis pain and pains and edema after fractures.

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