Re-epithelialization of porcine skin by the sweat apparatus

The behavior of the keratinocyte during the initial stages of cutaneous wound repair has been the subject of intense investigation. Most of these studies have focused on the lateral edges of wounds as the source of activated keratinocytes. Less attention has been directed towards elucidating the role of the appendageal structures as sources of keratinocytes for re-epithelialization, particularly the sweat apparatus. Surgical wounds of specific depths were created in pig skin, above and below hair follicles, and wound healing was allowed to take place in a setting in which lateral ingrowth of keratinocytes by migration was prevented. In this manner, all re-epithelialization occurred from residual appendageal structures. In those wounds where only sweat gland elements remained, an epithelium formed that had clinical, morphologic, and protein electrophoretic features closer to palmar/plantar or mucosal-like epithelia. In contrast, wounds that retained elements of the hair follicle healed faster and the resultant epithelium clinically, morphologically, and biochemically resembled the surrounding nonwounded epidermis. These findings establish that the sweat apparatus is capable of re-epithelializing the skin surface after a major cutaneous wound, but may not be capable of mimicking the epidermis.

Heterogeneity of the Ro/SSA antigen and autoanti-Ro/SSA response: evidence of the four antigenically distinct forms

Precipitating antibodies to the Ro/SSA antigen occur in the sera of 40% of patients with systemic lupus erythematosus (SLE) and in 40-70% of the sera of patients with primary Sjögren's syndrome. Previous work has shown that lymphocyte extracts contain two Ro/SSA antigens with protein moieties of 60 kD and 52 kD and that erythrocyte haemolysate contain two analogous but antigenically distinct Ro/SSA molecules of 60 kD and 54 kD. Frequency analysis of the various specificities in 43 sera with precipitating anti-Ro/SSA and studies with affinity-eluted antibodies suggest that the lymphocyte 60 kD and erythrocyte 60 kD Ro/SSA molecules are related as are the lymphocyte 52 kD and erythrocyte 54 kD Ro/SSA proteins. Anti-Ro/SSA sera when accompanied by other precipitins (anti-La/SSB and anti-U1RNP) react preferentially with certain Ro/SSA isoforms. Evidence is also presented for a 45 kD form of Ro/SSA. These data suggest that the antigenic heterogeneity of the Ro/SSA antigen is immunologically relevant and that there are two families of Ro/SSA antigens; one comprising of the two 60-kD proteins in the erythrocyte and lymphocyte and the other the erythrocyte 54 kD and lymphocyte 52 kD Ro/SSA proteins, respectively.

Differences in the fine specificity of anti-Ro (SS-A) in relation to the presence of other precipitating autoantibodies

In sera from patients with systemic lupus erythematosus or Sjögren's syndrome, we determined the fraction of antibody that remained reactive with human Ro (SS-A) after absorption with bovine spleen extract, and the reactivity with the 60-kd and 54-kd red blood cell Ro (SS-A) bands by Western blot. Of the 3 groups of sera studied, those containing anti-Ro (SS-A) alone had the highest degree of reactivity with human Ro (SS-A) after absorption with bovine spleen extract, followed, in descending order, by sera containing anti-Ro (SS-A) and anti-La (SS-B), and sera containing anti-Ro (SS-A) and anti-nuclear RNP. The groups of sera could be distinguished on this basis. Sera with anti-Ro (SS-A) and anti-nuclear RNP could also be distinguished from the other 2 types of sera by their uniform and preferential reactivity with the 60-kd red blood cell Ro (SS-A), by Western blot analysis. These findings indicate that there are both qualitative and quantitative differences, associated with the presence of other autoantibodies, in the fine specificity of anti-Ro (SS-A) sera.

Heterogeneity of the Ro/SSA antigen. Different molecular forms in lymphocytes and red blood cells

Ro(SSA) is an intracellular ribonucleoprotein against which autoantibodies are found in a portion of patients with Sjögren's syndrome and systemic lupus erythematosus. A form of Ro(SSA) is described in red blood cells that shares a line of identity with purified Ro(SSA) from bovine spleen and human lymphocytes in counterimmunoelectrophoresis, but has different molecular properties. Ro(SSA) from red blood cells exists in association with only two small RNAs as opposed to four in other cell types, as determined by RNA extraction of protein A-assisted immunoprecipitates. In addition to the common 60-kD Ro(SSA) protein, Western blot analysis revealed an additional 52-kD protein in lymphocytes and a 54-kD protein in red blood cells. The 60-kD form of Ro(SSA) in red cells was found to be antigenically distinct from that in the lymphocyte, because sera were identified that bound each exclusively. Finally, a rabbit antibovine Ro(SSA) serum distinguished red cell from lymphocyte Ro(SSA). These results suggest two distinctive populations of Ro(SSA) proteins and distributions of Ro(SSA) RNAs in the lymphocyte and red blood cell.

Complement C4 fixation by the anti-La(SSB) found in normal donors and in patients with systemic lupus erythematosus

The discovery that a common systemic lupus erythematosus (SLE) autoantibody (anti-La/SSB) occurs in normal individuals has made it possible to compare the specific complement binding capacity of normal autoantibody with SLE patient autoantibody. Normal donors with elevated levels of anti-La(SSB) binding were compared to negative normal donors and to 3 patients with SLE with high levels of anti-La(SSB) binding in assays for anti-La(SSB) and for the capacity of anti-La(SSB) to bind C4. The anti-La(SSB) found in normal sera and in SLE patient sera had no identical specific capacity to fix C4. For the case of anti-La(SSB), the autoantibody structure in relation to its specific capacity to activate complement, at least to the extent of fixing C4, does not differentiate SLE patients from normal individuals with this autoantibody.