We studied the effect of the same genetic but different environmental factors on total immunoglobulin and specific antibody levels in twins reared apart. Sera were analyzed from 26 monozygotic (MZ) and 10 dizygotic (DZ) twin pairs, who were separated on average 2 mo after birth and reared apart. Total IgM, IgG, and IgA were measured by single radial diffusion. Specific antibodies of each isotype to tetanus toxoid, and to polyvalent and type 14 pneumococcal capsular polysaccharides were measured by a solid-phase antigen-enzyme-labeled antiIg immunoassay. One-way analysis of variance showed intrapair total Ig and antibody levels to be more highly correlated in MZ compared with DZ twins. Our results indicate that genetic factors are more important than environment in regulating these humoral immune responses.

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Circulating immune complexes were characterized from 25 sera obtained from five patients with polyarteritis nodosa and three with cutaneous venulitis associated with hepatitis B virus infection. Complexes were isolated by polyethylene glycol and conglutinin-anticonglutinin precipitation methods and were analyzed for HBsAg and anti-HBsAg. Low pH was used to dissociate the complexes, and components were separated into antigen and antibody fractions by using immobilized protein A. In this study, three observations were significant: 1) complexes were frequent and quantitatively more in cutaneous venulitis than in polyarteritis; 2) the levels of HBsAg in the antigen fractions of polyarteritis were greater and correlated with the clinical improvement of the disease; the serum levels of HbsAg remained the same throughout the course of the disease; and 3) complexes from polyarteritis were not completely dissociable at pH 2.6 compared with those from patients with cutaneous venulitis and chronic active hepatitis. The antigen fractions electrophoresed in polyacrylamide gel with SDS demonstrated 6 to 10 protein bands with m.w. ranging between 17,000 and 120,000 daltons. To precisely define the polypeptide antigen moiety involved in the immune complex formation, a transfer blotting technique was used employing human anti-HBsAg globulin as probe. Polypeptides with m.w. 97,000, 49,000, and 23,000 were found to form complexes in both groups of patients.

Summary The technique of counterimmunoelectrophoresis (CIE) has been adapted for detection of serum precipitins to calf thymus (CT) DNA in patients with SLE, discoid LE, miscellaneous connective tissue and infectious diseases, and control populations. Of seventy‐eight LE patients, 58% demonstrated anti‐ss DNA precipitins, and 20% exhibited anti‐ds DNA precipitins. Good correlation was noted between the presence of ss DNA precipitins and ss DNA binding values determined by the more sensitive ammonium sulphate precipitation assay. Depressed total serum haemolytic complement activity in CH50 u/ml was noted in 64% of sera exhibiting ss DNA precipitins and 38% of those with negative ss DNA precipitins. There was a strong association, however, between ds DNA precipitins and depressed serum complement levels. Although less sensitive than primary binding assays, CIE can be used as a rapid and simple screening test for detection of circulating anti‐native and denatured CT DNA precipitins. CT DNA serum precipitins are present in a significantly higher percentage of SLE patients when compared with other disease states and normal control populations.