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.

Antibodies from IgA and IgM classes that recognize Naegleria fowleri (Nf) proteins were detected by the ELISA assay in serum and saliva from three groups of people: (i) subjects with upper respiratory tract infections (URTI) living in the parasite-endemic area, (ii) healthy persons from the same area, and (iii) healthy persons from a parasite-nonendemic area. In serum and in saliva the titers of IgA antibodies to Naegleria fowleri in the group of patients with URTI was significantly higher than that of the healthy group in the parasite-endemic area; also the titers of IgM antibodies in serum were significantly higher in patients. On the contrary, in saliva the antibodies were higher in healthy people from the parasite-endemic area. In all cases the subjects from the parasite-nonendemic area had lower antibody titers in serum and saliva.

A 34-year-old man had polar extremes of B cell dysfunction: systemic lupus erythematosus evolving into common variable hypogammaglobulinemia. He presented in 1974 with seizures and six other criteria for systemic lupus erythematosus; his antinuclear antibody titer was 1:1024 and IgG level, 2870 mg/dL. After 5 months of immunosuppressive treatment, a 79% decrease in serum IgG and 95% decrease in IgA levels occurred and manifestations of systemic lupus erythematosus disappeared. Six years later, he developed panhypogammaglobulinemia, had recurrent sinopulmonary infections, and showed nodular lymphoid hyperplasia on rectal biopsy. For comparison, serum immunoglobulin concentrations were measured serially in 13 other patients with systemic lupus erythematosus. Three developed severe depressions of these levels, two with IgG levels less than 300 mg/dL and one with an IgA level of 8 mg/dL. These decreases were transient, related to treatment, and not associated with infections. Daily high-dose prednisone therapy (60 mg/d) rather than treatment with cytotoxic drugs correlated with decreased immunoglobulin concentrations.

Antibodies from IgA and IgM classes that recognize Naegleria fowleri (Nf) proteins were detected by the ELISA assay in serum and saliva from three groups of people: (i) subjects with upper respiratory tract infections (URTI) living in the parasite-endemic area, (ii) healthy persons from the same area, and (iii) healthy persons from a parasite-nonendemic area. In serum and in saliva the titers of IgA antibodies to Naegleria fowleri in the group of patients with URTI was significantly higher than that of the healthy group in the parasite-endemic area; also the titers of IgM antibodies in serum were significantly higher in patients. On the contrary, in saliva the antibodies were higher in healthy people from the parasite-endemic area. In all cases the subjects from the parasite-nonendemic area had lower antibody titers in serum and saliva.

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