Silicone gel filled breast implants and connective tissue disease: an overview

OBJECTIVE

To review the literature examining the association of silicone gel filled implants and connective tissue disease.

METHODS

Computerized literature searches and manual review of bibliographies.

RESULTS

Numerous concerns have arisen regarding the safety of silicone gel filled breast implants. The structure of these prostheses is reviewed. Silicones are not biologically inert. Injectable as well as implantable silicones have proven capable of eliciting inflammatory and fibroproliferative responses. Silicone leakage from silicone gel filled implants is well documented as is distant migration of silicone in the host. In the past decade, over 60 cases of connective tissue disease following mammoplasty with silicone gel filled implants have been reported. About half of these patients developed scleroderma or scleroderma-like illnesses. This reported overrepresentation of scleroderma compared to other rheumatic diseases mimics the Japanese experience with injectable silicones. Possible biological rationale for the association is presented.

CONCLUSION

The physical and biological properties of silicone gel filled implants and their behavior in vivo is compatible with the hypothesis that they may contribute to the development of connective tissue disease. The association seems most likely with scleroderma; however, there is as yet inadequate epidemiological data to definitively establish causality.

Assessing the impact of self-efficacy beliefs on adaptation to rheumatoid arthritis

This article examines the influence of self-efficacy beliefs on problem-solving coping, functional disability, and psychological well-being for 101 recently diagnosed adult patients with rheumatoid arthritis (RA). Data were drawn from a longitudinal study of psychosocial adaptation to the onset of RA. Self-efficacy beliefs were associated with less functional disability assessed concurrently and 1 year later. Self-efficacy beliefs were also associated with greater use of problem-solving coping 1 year later. There was an interaction between pain and self-efficacy beliefs in the prediction of depression 1 year later: at low pain, self-efficacy beliefs were unrelated to depression, but at higher levels of pain, greater self-efficacy was related to greater depression. Finally, problem-solving coping mediated the relationship between disability and initial self-efficacy beliefs. The distinct patterns that emerge for pain, self-efficacy beliefs, and coping, with respect to functional status as compared to psychological status, are discussed.

The genetics of rheumatic fever: relationship to streptococcal infection and autoimmune disease

A large body of evidence suggests that patients with rheumatic fever immunologically respond abnormally both at a humoral and cellular level to streptococcal antigens cross-reactive with mammalian tissues. Implicit in this concept is that this abnormal immune response is genetically programmed. Using a monoclonal antibody called D8/17, a B cell marker has now been identified in 90-100% of all patients with rheumatic fever tested in 5 different geographical and ethnic populations. This trait appears to be inherited in an autosomal recessive fashion. This recognition of a B cell marker unique to individuals with rheumatic fever has important public health implications with respect to identification of individuals susceptible to rheumatic fever, possible prevention of disease and the recognition of prime candidates for future streptococcal vaccines.

Social support as a double-edged sword: the relation of positive and problematic support to depression among rheumatoid arthritis patients

This study considers social network interactions as a potential source of both stress and support for individuals coping with a chronic illness. The sample consisted of 101 recently-diagnosed rheumatoid arthritis patients. Symptoms of depression were assessed using the Center for Epidemiologic Studies Depression scale. Hierarchical multiple regression analyses examined the conjoint effects of social support and problematic interactions on symptoms of depression. Receipt of positive or helpful support from close friends and family was related to lower depression; receipt of problematic support was related to increased depression. A positive x problematic support interaction suggested that the costs of problematic support do not cancel out the benefits of positive support. Patients who reported both little support and a greater degree of problematic interactions experienced the highest level of symptoms. The findings emphasize the need to consider positive and negative aspects of support transactions conjointly in assessing their stress-reducing and health-protective potential.

The role of Fc gamma receptors in mononuclear phagocyte system function

Abnormalities in host mechanisms for the handling of immune complexes (IC) may promote both tissue deposition of pathogenic complexes and interaction of complexes with other immunocompetent cells. Although immune adherence of complexes to erythrocytes may be decreased in patients with autoimmune disease, the significance of this decrease for overall immune complex handling is unclear since many IC release rapidly from the erythrocytes. Little is known about the role of complement receptors in IC uptake by phagocytes. In contrast, the observations of defective Fc gamma receptor-mediated uptake of IgG ligand-coated erythrocytes (one model for erythrocyte-bound complexes) by fixed tissue macrophages in SLE patients demonstrate the role of Fc gamma receptors in the uptake of these complexes. Although partly acquired and related to disease activity in SLE, the Fc-mediated clearance defect may also have a genetic component. Inherited differences in Fc gamma function may reflect structural polymorphisms of the involved Fc receptors. The emerging picture of Fc gamma receptor structural diversity - several different receptor families (Fc gamma RI, Fc gamma RII and Fc gamma RIII) each with different isoforms, the potential for different glycoforms and cell anchoring mechanisms, and allelic variations within the isoforms - provides the basis for structure/function relationships which have clear implications for autoimmune diseases with abnormal Fc receptor function.

Presence of a non-HLA B cell antigen in rheumatic fever patients and their families as defined by a monoclonal antibody

Numerous investigators have suspected that there is a genetic predisposition to rheumatic fever (RF). In this context we have recently produced a series of monoclonal antibodies directed against B cells obtained from RF patients one of which, labeled D8/17, identifies a B cell antigen present in 100% of all RF patients studied. While the highest percentage of positive cells were exhibited by RF probands (33.5% +/- SE), the percentage of cells in unaffected siblings and parents was 14.6 and 13%, respectively. The percentage of positive cells in APSGN probands, unaffected siblings, and parents was 2.96, 3.86, and 2.8%, respectively. A low level of B cells (5-7%) bearing the D8/17 marker was seen in control patients. The segregation pattern of the phenotypes defined by the percentage of D8/17 positive cells within HLA-typed RF families are consistent with an autosomal recessive mode of inheritance not associated with the human MHC system. We postulate that these phenotypes indicate the presence of at least one necessary genetic factor for susceptibility to RF.

Altered phagocytosis by monocytes from HLA-DR2 and DR3-positive healthy adults is Fc gamma receptor specific

Fc gamma receptor-dependent mononuclear phagocyte system (MPS) clearance of opsonized erythrocytes is prolonged in healthy adults with the class II alloantigens HLA-DR2, DR3, or DQw1, despite normal receptor-specific Fc ligand binding by monocytes in these groups. To investigate the basis for the MPS dysfunction, we determined the phagocytic capacity of blood monocytes from 66 disease-free adults and analyzed the data according to the HLA type of the subjects. The data demonstrate decreased phagocytosis of IgG-sensitized erythrocytes (EA) by monocytes from HLA-DR2, DR3, or DQw1-positive subjects compared with normals without these B cell alloantigens (2.87 +/- 0.83 erythrocytes/monocyte vs 3.87 +/- 1.05, p less than 0.004; 3.01 +/- 0.94 vs 3.87 +/- 1.05, p less than 0.02; 3.18 +/- 0.89 vs 3.87 +/- 1.05, p less than 0.02, respectively). Because HLA-DR2 and DQw1 are in linkage disequilibrium, we compared EA phagocytosis in subjects with DQw1 alone to normals without HLA-DR2, DR3, or DQw1. Among subjects positive only for DQw1, no significant decrease in phagocytosis could be seen (3.46 +/- 0.95 vs 3.87 +/- 1.05, p = NS). To determine whether these differences represented an Fc receptor-specific dysfunction or a more generalized decrease in phagocytic activity, we compared the quantitative phagocytosis of EA with that of neuraminidase-treated erythrocytes (EN), which is Fc receptor independent and beta-glucan receptor mediated. No segregation of phagocytic capacity for EN by HLA class II phenotypes could be demonstrated (DR2, 2.68 +/- 1.30 erythrocytes/monocyte; DR3, 2.95 +/- 1.30; DQw1, 2.84 +/- 1.15; others, 3.06 +/- 1.14). Our data indicate that the decrease in phagocytosis by blood monocytes from normal individuals with HLA-DR2 or DR3, the class II alloantigens associated with systemic lupus erythematosus and other autoimmune diseases, is specific for the Fc receptor-mediated process. This alteration of Fc receptor function among immunogenetically defined individuals may contribute to their predisposition to autoimmune disease. These differences may also apply to other Fc receptor-initiated cellular functions.

Altered phagocytosis by monocytes from HLA-DR2 and DR3-positive healthy adults is Fc gamma receptor specific

Fc gamma receptor-dependent mononuclear phagocyte system (MPS) clearance of opsonized erythrocytes is prolonged in healthy adults with the class II alloantigens HLA-DR2, DR3, or DQw1, despite normal receptor-specific Fc ligand binding by monocytes in these groups. To investigate the basis for the MPS dysfunction, we determined the phagocytic capacity of blood monocytes from 66 disease-free adults and analyzed the data according to the HLA type of the subjects. The data demonstrate decreased phagocytosis of IgG-sensitized erythrocytes (EA) by monocytes from HLA-DR2, DR3, or DQw1-positive subjects compared with normals without these B cell alloantigens (2.87 +/- 0.83 erythrocytes/monocyte vs 3.87 +/- 1.05, p less than 0.004; 3.01 +/- 0.94 vs 3.87 +/- 1.05, p less than 0.02; 3.18 +/- 0.89 vs 3.87 +/- 1.05, p less than 0.02, respectively). Because HLA-DR2 and DQw1 are in linkage disequilibrium, we compared EA phagocytosis in subjects with DQw1 alone to normals without HLA-DR2, DR3, or DQw1. Among subjects positive only for DQw1, no significant decrease in phagocytosis could be seen (3.46 +/- 0.95 vs 3.87 +/- 1.05, p = NS). To determine whether these differences represented an Fc receptor-specific dysfunction or a more generalized decrease in phagocytic activity, we compared the quantitative phagocytosis of EA with that of neuraminidase-treated erythrocytes (EN), which is Fc receptor independent and beta-glucan receptor mediated. No segregation of phagocytic capacity for EN by HLA class II phenotypes could be demonstrated (DR2, 2.68 +/- 1.30 erythrocytes/monocyte; DR3, 2.95 +/- 1.30; DQw1, 2.84 +/- 1.15; others, 3.06 +/- 1.14). Our data indicate that the decrease in phagocytosis by blood monocytes from normal individuals with HLA-DR2 or DR3, the class II alloantigens associated with systemic lupus erythematosus and other autoimmune diseases, is specific for the Fc receptor-mediated process. This alteration of Fc receptor function among immunogenetically defined individuals may contribute to their predisposition to autoimmune disease. These differences may also apply to other Fc receptor-initiated cellular functions.

Defective mononuclear phagocyte function in systemic lupus erythematosus: dissociation of Fc receptor-ligand binding and internalization

Fc receptor-mediated mononuclear phagocyte system (MPS) clearance is impaired in systemic lupus erythematosus (SLE) and may contribute to the pathogenesis of the immune complex disease. To investigate the basis of MPS dysfunction, we have examined concurrent in vivo and in vitro Fc receptor function in 22 patients with SLE and 23 disease-free adults. Blood monocyte Fc receptor binding was increased rather than decreased as predicted by the saturation hypothesis of MPS blockade. Rosette formation of IgG-sensitized bovine erythrocytes (EA) with monocytes demonstrated increased Fc receptor-ligand binding in SLE (percent rosettes: 40 +/- 12 vs 27 +/- 8, p less than 0.001). Scatchard analysis of the binding of radiolabeled IgG oligomers to SLE monocytes indicated a mean receptor number 30% higher than control, although this did not reach statistical significance. Despite enhanced Fc receptor-ligand (EA) binding, Fc-mediated phagocytosis of EA was decreased in SLE (1.7 +/- 0.7 erythrocytes/monocytes/hour vs 2.6 +/- 1.0, p less than 0.004). This decrease in phagocytosis by blood monocytes from SLE patients was significantly greater than that attributable to the predominance in SLE of individuals with certain HLA B cell alloantigens and intrinsically lower phagocytic rates (p less than 0.05 for all groups). This decrease therefore represents a disease-acquired characteristic. Furthermore, the phagocytic rate of the four SLE patients with marked prolongation in MPS clearance was significantly lower than that of the eight patients with near normal clearance values (p less than 0.01). Saturation of Fc receptors by immune complexes does not explain impaired immune clearance in SLE. Our results indicate that despite increased binding of the EA ligand, Fc receptor-mediated phagocytosis is markedly impaired in SLE monocytes. This impairment cannot be explained on the basis of HLA-related differences in phagocytosis among lupus patients. The defect in phagocytosis of EA is most profound in those patients with the most significantly impaired MPS clearance. Thus, the dissociation of receptor-ligand binding and receptor-mediated internalization may contribute significantly to the in vivo clearance defect in SLE.

Defective mononuclear phagocyte function in systemic lupus erythematosus: dissociation of Fc receptor-ligand binding and internalization

Fc receptor-mediated mononuclear phagocyte system (MPS) clearance is impaired in systemic lupus erythematosus (SLE) and may contribute to the pathogenesis of the immune complex disease. To investigate the basis of MPS dysfunction, we have examined concurrent in vivo and in vitro Fc receptor function in 22 patients with SLE and 23 disease-free adults. Blood monocyte Fc receptor binding was increased rather than decreased as predicted by the saturation hypothesis of MPS blockade. Rosette formation of IgG-sensitized bovine erythrocytes (EA) with monocytes demonstrated increased Fc receptor-ligand binding in SLE (percent rosettes: 40 +/- 12 vs 27 +/- 8, p less than 0.001). Scatchard analysis of the binding of radiolabeled IgG oligomers to SLE monocytes indicated a mean receptor number 30% higher than control, although this did not reach statistical significance. Despite enhanced Fc receptor-ligand (EA) binding, Fc-mediated phagocytosis of EA was decreased in SLE (1.7 +/- 0.7 erythrocytes/monocytes/hour vs 2.6 +/- 1.0, p less than 0.004). This decrease in phagocytosis by blood monocytes from SLE patients was significantly greater than that attributable to the predominance in SLE of individuals with certain HLA B cell alloantigens and intrinsically lower phagocytic rates (p less than 0.05 for all groups). This decrease therefore represents a disease-acquired characteristic. Furthermore, the phagocytic rate of the four SLE patients with marked prolongation in MPS clearance was significantly lower than that of the eight patients with near normal clearance values (p less than 0.01). Saturation of Fc receptors by immune complexes does not explain impaired immune clearance in SLE. Our results indicate that despite increased binding of the EA ligand, Fc receptor-mediated phagocytosis is markedly impaired in SLE monocytes. This impairment cannot be explained on the basis of HLA-related differences in phagocytosis among lupus patients. The defect in phagocytosis of EA is most profound in those patients with the most significantly impaired MPS clearance. Thus, the dissociation of receptor-ligand binding and receptor-mediated internalization may contribute significantly to the in vivo clearance defect in SLE.

Immunogenetic and clinical findings in idiopathic pulmonary fibrosis. Association with the B-cell alloantigen HLA-DR2

In order to assess the role of immunogenetic factors in the pathogenesis of idiopathic pulmonary fibrosis (IPF), HLA-A, B, C, and DR typing was performed on 20 Caucasian patients with IPF seen from 1978 to 1980 and in 200 healthy blood donors. An increase in the frequency of the B-cell alloantigen, HLA-DR2, was observed; HLA-DR2 was found in 65% of patients with IPF compared with 26% of the control subjects (corrected p value = 0.005, chi-square = 11.476, relative risk = 5.286). Although not significant, increases were observed in HLA-B7 and HLA-A3, antigens known to be in linkage disequilibrium with HLA-DR2. The HLA-DR2 was observed in 12 of 14 patients with "ground glass linear" and "cystic honeycombing" radiographic patterns, whereas it was observed in only 1 of 6 patients with "ascinar nodular" radiographic patterns (p = 0.01). No other correlation was observed between HLA type and clinical, laboratory, or pathologic parameters. We conclude that immunogenetic factors, perhaps genes within the major histocompatibility complex, are relevant to the pathogenesis of IPF.

Impaired fc-mediated mononuclear phagocyte system clearance in HLA-DR2 and MT1-positive healthy young adults

Normal individuals with an HLA haplotype containing either DR2, MT1, or B8/DR3 are more likely to have abnormally prolonged Fc receptor-mediated mononuclear phagocyte system (MPS) clearance of IgG-sensitized autologous erythrocytes than their normal counterparts without such haplotypes. Although measurement of Fc receptor binding by rosette formation and saturable IgG aggregate binding revealed no differences among groups, Fc receptor-mediated phagocytosis of IgG-sensitized bovine erythrocytes by monocytes was decreased in the DR2-positive and MT1-positive individuals. The basal in vivo MPS clearance in normal individuals may be immunogenetically determined and may reflect differences in phagocytic rates.

Familial systemic lupus erythematosus in males

Several families in which systemic lupus erythematosus predominates in males are presented. The disease primarily manifested itself in the sons and in the male parents. Females in some of the families had other autoimmune diseases such as idiopathic thrombocytopenic purpura or symptoms suggestive of a lupus diathesis. It is suggested that the sons inherited the disease from their fathers in these families. The disease in the patients had some similarity to the disease in BXSB mice.

Defective Fc receptor-mediated function of the mononuclear phagocyte system in lupus nephritis

To determine whether patients with systemic lupus erythematosus and nephritis have more profound defects in mononuclear phagocyte system clearance than their counterparts without renal disease, we studed Fc receptor-mediated splenic clearance function in 32 patients. Clearance half-times were prolonged in patients with lupus erythematosus compared with those in normal controls (p less than 0.0001) and longer in patients with renal disease than in those without (p less than 0.025). Both renal (tau = 0.45, p less than 0.0002) and nonrenal (tau = 0.35, p less than 0.003) disease activity were significantly but independently associated with clearance half-times. When matched for nonrenal activity, patients with nephritis had greater clearance dysfunction than their counterparts without renal disease. Circulating immune complexes did not correlate with clearance for all patients. Neither B8 nor DR3 histocompatibility antigen markers differentiated the renal and nonrenal disease subgroups. The greater Fc receptor-mediated clearance dysfunction, which occurs in patients with lupus erythematosus and nephritis, could lead to enhanced glomerular deposition of immune complexes as a primary event, or as a secondary event amplifying previously established lesions.

Three siblings with scleroderma (systemic sclerosis) and two with Raynaud's phenomenon from a single kindred

A kindred is reported which contains 3 siblings with scleroderma, 2 siblings with Raynaud's phenomenon, and 2 first-degree relatives with histories suggestive of connective tissue syndromes. Studies of microvascular morphology and flow, serum endothelial cytotoxic activity, antinuclear antibodies, and HLA haplotypes in 18 relatives and 6 spouses revealed that 4 of 5 affected siblings expressed the HLA-DRw4 antigen, which was also present in 2 of 3 asymptomatic relatives whose serum contained endothelial cytotoxic activity. The evidence for an inherited susceptibility to scleroderma is reviewed.

Peripheral blood Ia-positive T cells. Increases in certain diseases and after immunization

The Ia antigens, usually expressed primarily on B lymphocytes, are found on a small percentage of normal peripheral blood T cells (average 2.6% by fluorescence and 10.8% by rosette assay). Elevated levels up to 40% by both assays were observed in a high proportion of patients with rheumatoid arthritis. Increases also were found in patients with systemic lupus erythematosus and various types of infections. The increases were evident with a specific heteroantiserum, a hybridoma reagent, and DR specific alloantisera. Normal levels were present in multiple sclerosis and an assortment of metabolic and other disorders. A rise in similarly positive T cells occurred in normal individuals after immunization with tetanus toxoid or PPD. The cells primarily involved in all of these instances were small lymphocytes, which stained relatively weakly with the fluorescent reagents and were readily distinguishable from T-cell blasts. They were found to be enriched in isolated T gamma fractions but were also found in other T cells. The accumulated evidence indicated that these cells represent an expansion of one or more subsets of T cells found in normal individuals, and that their level in the peripheral blood may serve as an index of immunological stimulation.

Chronic Lyme arthritis. Clinical and immunogenetic differentiation from rheumatoid arthritis

Ten patients with Lyme arthritis have developed chronic involvement of one or both knees. Lyme arthritis was diagnosed by onset with erythema chronicum migrans (six patients); residence in Lyme, Connecticut (eight); seasonal onset in summer and early fall (nine); early periods of short recurrent attacks (nine); absence of rheumatoid factor (nine); and absence of symmetrical polyarthritis, morning stiffness, subcutaneous nodules, or antinuclear antibodies (in all). Five patients had synovectomies; pannus formation and underlying cartilage erosion were present in all. Seven of the 10 patients had the same B-cell alloantigen, DRw2 (frequency in normal control subjects, 22% [P less than 0.005]), but did not have an increased frequency of the alloantigens associated with rheumatoid arthritis. Chronic Lyme arthritis, the result of an apparent tick-transmitted infection, resembles rheumatoid arthritis pathologically but generally differs from it in both prearticular and immunogenetic characteristics.

Association of HLA-DRw2 with autoimmune thrombocytopenic purpura

Peripheral blood lymphocytes from 38 patients with autoimmune thrombocytopenic purpura (AITP) were tested for HLA-A, -B, and -C alloantigens. Isolated B lymphocytes from 20 of these patients were tested for HLA-DRw (Ia) alloantigens. The profile of HLA alloantigens in the patients with AITP was significantly different from that of a matched control population. The most significant finding was the presence of the HLA-DRw2 alloantigen in 75% of patients as compared with 23% in the control population, P less than 0.001, relative risk 10.0 (A relative risk of 1 would indicate no association between the presence of the antigen and the disease.) The co-occurrence of either A3 and B7 (known to be in linkage disequilibrium with DRw2) or A26 and Bw38 was significantly increased as compared with the control population (P less than 0.001). Of the patients positive for DRw2, 47% had the association A26 and Bw38 as compared with the control population association incidence of 21% (P less than 0.1). Thus, in the patient population, A26-Bw38 appears to be a haplotype that is in linkage disequilibrium with DRw2 (as presumably is the case with A3-B7). These data indicate that a predisposition to AITP is inherited with a DRw2 gene of the major histocompatibility system.

Disease associations of the Ia-like human alloantigens. Contrasting patterns in rheumatoid arthritis and systemic lupus erythematosus

Increasing evidence has been obtained of the special value of Ia-like B-cell alloantisera for demonstrating disease associations with histocompatibility antigens. This was particularly evident for the study of the immunogenetics of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), two conditions frequently considered related. The profiles of antigens recognized by the alloantisera in patients from each disease group was distinctive. Two types of alloantisera were obtained that illustrated the divergence between the twod iseases. One type showed a higher than normal incidence in RA but lower than normal in SLE; the other showed a higher incidence in SLE. While these sera were not totally defined, evidence was obtained that the SLE-reactive alloantiserum related to two alleles of the major histocompatibility complex DRw2 and DRw3, while the RA-reactive alloantiserum related to a common specificity shared by cells positive for either DRw4, DRw7, or DRw10. The data indicate that immunogenetic factors are relevant to the development of both RA and SLE, but that these are distinct for each disease.

Expression of Ia-like antigens on cultured human malignant melanoma cell lines

Human malignant melanoma cell lines were found to bear Ia-like cell surface determinants demonstrable by hetero- or alloantisera and by direct identification of the characteristic bimolecular glycoprotein complex. Immunoprecipitation confirmed the presence of Ia determinants on the bimolecular complex. The quantity of Ia molecules determined by these methods and by absorption experiments was relatively constant for each cell line. Among different lines, however, the amount of Ia antigens ranged from a level equal to that expressed by B-cell lines to a small fraction of this amount. This variation in level of Ia contrasted with the more uniform amount of beta2-microglobulin detected on the cell surface. The Ia alloantigen specificity DRw2 was the most frequently encountered specificity. Ia determinants were also found on the surface of an epidermoid carcinoma line, but not on various other cell lines of normal or neoplastic origin.

Contrasting patterns of newer histocompatibility determinants in patients with rheumatoid arthritis and systemic lupus erythematosus

The Ia alloantigens as measures of different alleles of loci in the major histocompatibility complex were determined in patients with systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA). The Ia specificities of reagents used were defined by their pattern of reaction with lymphoblastoid lines derived from normal donors homozygous for HLA-D determinants. The reagent specificities included those associated with a single Dw type as well as those reacting with a single specificity shared by several Dw types. Patients with RA had a marked elevation in the frequency of alloantigens detected by reagent sera that recognize various determinants shared by cell lines from HLA-Dw4, Dw7, or Dw10 individuals (Ia 4-7-10). The frequency of mixed lymphocyte culture alleles Dw4 and Dw10 was found to be increased; however this elevation did not approach the higher frequency for the serologically determined antigens of the Ia 4-7-10 group. In contrast, patients with SLE had an increased frequency of reactions with the reagent alloantisera defined by reactions with either HLA-Dw2 or Dw3 positive cell lines. The data suggest that immunogenetic factors are relevant to both groups of patients, but that these are entirely distinct for each disease.

The identification of HL-A antigens on fresh and cultured human endothelial cells

Human endothelial cells were obtained from the umbilical cord veins of 16 newborns by methods previously described and tested for HL-A antigens by a microcytotoxicity method. HL-A antigens were present on all endothelial cell lines tested. When the HL-A phenotypes of fresh endothelial cells and autologous fetal lymphocytes were compared, a concordance of 70% was observed. When the HL-A phenotypes of maternal lymphocytes and fresh endothelial cells were compared, a maternal contribution to the endothelial cell phenotype was evident in 72% of the possible commmon antigens. Some HL-A antigens were deleted from 11 of 16 endothelial cell lines that were re-typed after 2 weeks in tissue culture. The majority (90%) of deleted antigens were from the second HL-A locus. When three lines of endothelials cells were again re-typed after 6 weeks in culture, no further changes in antigenicity were noted. These findings: a) demonstrate that HL-A antigens are present on human endothelium and suggest that endothelial cells are actively involved in establishing the immunogenicity of a graft, and b) demonstrate that the HL-A antigens on human endothelial cells may be modulated by in vitro culture.

The Identification of HL-A Antigens on Fresh and Cultured Human Endothelial Cells

Human endothelial cells were obtained from the umbilical cord veins of 16 newborns by methods previously described and tested for HL-A antigens by a microcytotoxicity method. HL-A antigens were present on all endothelial cell lines tested. When the HL-A phenotypes of fresh endothelial cells and autologous fetal lymphocytes were compared, a concordance of 70% was observed. When the HL-A phenotypes of maternal lymphocytes and fresh endothelial cells were compared, a maternal contribution to the endothelial cell phenotype was evident in 72% of the possible common antigens. Some HL-A antigens were deleted from 11 of 16 endothelial cell lines that were re-typed after 2 weeks in tissue culture. The majority (90%) of deleted antigens were from the second HL-A locus. When three lines of endothelials cells were again re-typed after 6 weeks in culture, no further changes in antigenicity were noted. These findings: a) demonstrate that HL-A antigens are present on human endothelium and suggest that endothelial cells are actively involved in establishing the immunogenicity of a graft, and b) demonstrate that the HL-A antigens on human endothelial cells may be modulated by in vitro culture.