In vivo antinuclear antibody of the skin: diagnostic significance and association with selective antinuclear antibodies.

Immunofluorescence microscopy of the skin has disclosed antibodies bound to epidermal cell nuclei in several connective tissue disorders. To establish the diagnostic potential of this phenomenon the results of immunofluorescence microscopy of biopsy specimens from 1651 subjects with various diseases and from 315 patients with systemic connective tissue disorders and related diseases were reviewed. It was found that the predictive value of the phenomenon for the presence of a systemic connective tissue disorder was, in general, 88%. Except for the homogeneous and thready patterns, which seldom appear, but are specific for SLE, in vivo antinuclear antibody (ANA) does not discriminate better between the various disorders than do serum antibodies. The presence of in vivo ANA in the skin was related to serum antibodies against non-histone nucleoproteins, but not to anti-dsDNA antibodies. Combined with the finding that antibodies against non-histone nucleoproteins can bind on the surface of human keratinocytes, this suggests that ANA of the skin occurs in vivo.

Does the degree of polymerization of haptoglobin influence the results of the radial immunodiffusion assay?

The degree of polymerization of haptoglobin (Hp) phenotypes 2-1 and 2-2 was studied. In individual samples the degree of polymerization tends to be positively correlated with the Hp concentration as determined by the radial immunodiffusion technique (RID), while an inverse relationship between the size of Hp polymers and the Hp concentration in RID was expected. After reductive cleavage of Hp, the apparent Hp concentration became higher in individual samples with different degrees of polymerization; the shift to higher values appeared to be independent of the degree of polymerization in samples of phenotypes Hp 2-1 and Hp 2-2. Consequently, the degree of polymerization as such does not have an impact on the outcome of RID at a technical level.

Fc receptors on rabbit lymphocytes. Existence of receptors for IgG antibody complexed with antigen; conditions for its detection.

The presence of Fc receptors (FcR) on rabbit peripheral blood leukocytes is demonstrated using rosette formation with an ox erythrocyte-antibody (EoxA) complex. The receptor is specific for the Fc fragment of IgG (neither IgM nor F (ab')2 anti-Eox mediates rosette formation) that is antigen-bound (aggregated rabbit IgG inhibits the rosette formation only transiently). The receptor is species-specific: guinea pig IgG/Eox, goat IgG/Eox and sheep IgG/Eox complexes do not show rosette formation, and goat IgG aggregates do not inhibit rosette formation. The origin of the target erythrocytes is of importance. Sheep erythrocytes are not useful, and within Eox large differences between donors were found. Rosette formation was only inhibited by pretreatment of the rosette-forming cells with homologous immune complexes, whereas the size of the antigen greatly influenced the degree of inhibition. The rabbit FcR is pronase-resistant, unlike the human and murine RcR. The interaction of IgG and the FcR is not inhibited by isolated C gamma 3 domains. Further evidence for the requirement of the whole Fc region was obtained in experiments where inhibition of the rosette formation was observed using antisera directed to the C gamma 3 and the C gamma 2 domain, respectively. Anti-Fab antiserum did not inhibit rosette formation. Results are discussed in relation to the mechanism of allotypic suppression.

Identification of rosette-forming cells in permanent preparations.

A method is described for the identification of leucocytes in permanent cytocentrifuge rosette preparations made with the fluorescent methyl green pyronin-SITS (MPS) staining technique. The percentages of rosettes in stained slides agree well with the results obtained with the conventional haemocytometer method. Application of the MPS staining to cytocentrifuge preparations permits reliable morphological differentiation between free and rosetting leucocytes, and should be particularly valuable in studies on lymphocyte subpopulations in patients.