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Serum IgD levels in 83 healthy adults were measured by a radioimmunoassay technique and analysed according to each subject's smoking habit. The IgD geometric mean in cigarette smokers was twice as high as in non-smokers (408.6 vs 202.0 μg/dl). Serum IgD levels of 1,000 μg/dl or greater were noted in 22% of smokers but in none of the rare smokers or non-smokers. In the smokers group, the highest mean IgD level was found in those who did not actively inhale the smoke (7626 μg/dl), followed by that in moderate smokers (5638 μg/dl), and was lowest in heavy smokers who inhaled the smoke (2830 μg/dl). The number of years a person smoked did not appear to have a significant effect on IgD levels. In exsmokers, the mean IgD level (199.8 μg/dl) was similar to that in non-smokers, suggesting reversibility of the IgD changes following cessation of smoking. It seems prudent that the smoking habit should be taken into consideration in the interpretation of serum IgD levels. [ABSTRACT FROM AUTHOR]

A 46-year-old woman with repeated skin infections, sore throats, laryngitis and abscesses was investigated because of low gammaglobulin on serum electrophoresis. When tested for ability to form antibodies to several antigens the patient did not respond to primary antigenic stimuli with Salmonella H or O antigens, or with keyhole limpet haemocyanin (KLH). However, she had a good secondary response to numerous agents with which she had previous contact (tetanus, diphtheria, polio and specific blood group substances). The selective impairment of cells capable of giving a primary immune response in the presence of intact memory cells gives support to the concept of a qualitative difference between these two types of cells. [ABSTRACT FROM AUTHOR]

Using a sensitive radioimmunoassay, it was demonstrated that autoantibodies to human thyroglobulin (hTg) did not activate complement upon interaction with solid phase adsorbed hTg. Since IgG4 immunoglobulins do not activate complement, we studied sera containing large amounts of anti-thyroglobulin (anti-Tg) with a sensitive radioimmunoassay for IgG4 anti-Tg. Antibodies of the IgG4 subclass were detected in the sera of each of the eight patients studied and not in control subjects. Quantitative assays of IgG4 anti-Tg were performed by comparing the removal of anti-Tg and total IgG4 during immunoadsorption of anti-Tg. The contribution of IgG4 anti-Tg antibodies to the total quantity of anti-Tg ranged from 6 to 30%, an amount inadequate to explain the lack of complement activation by anti-Tg. [ABSTRACT FROM AUTHOR]