Antibodies against the extracellular domain of bullous pemphigoid antigen 2 (BPAG2) are thought to play a key role in the pathogenesis of bullous pemphigoid (BP), the most frequent autoimmune bullous disease of the skin. Autoreactive T cell responses to BPAG2 were investigated in 16 BP patients and 24 healthy controls by coculture of PBMC with two recombinant BPAG2 proteins (extracellular domain of BPAG2). Primary in vitro T cell responses to BPAG2 were observed in 10/12 BP patients expressing the BP-associated HLA-DQB1*0301 allele and 8/10 DQB1*0301 positive healthy individuals. DQB1*0301 also restricted three autoreactive T cell lines from two BP patients and a healthy donor. In contrast, PBMC from 14 normal patients carrying HLA class II alleles other than DQB1*0301 were not stimulated by BPAG2. Autoreactive BPAG2-specific CD4 ϩ T cell lines and clones from five BP patients produced both Th1 and Th2 cytokines, whereas three autoreactive T cell lines from three DQB1*0301 positive normal patients produced exclusively IFN-␥ . The absence of BPAG2-specific Th2 cells in healthy individuals strongly suggests that autoreactive Th2 responses to BPAG2 are restricted to BP patients and may thus be critical in the pathogenesis of BP. (

Soluble HLA-G (sHLA-G) molecules are found in the peripheral blood of healthy females and males, in cord blood and in amniotic fluids and discussed to be a mediator in maternal-fetal tolerance. In this study we investigated whether there are allele-specific differences in expression of sHLA-G molecules. For this, the sHLA-G plasma concentrations of 94 healthy unrelated individuals were measured by ELISA and correlated to their HLA-G genotypes, as determined by sequence analysis of exon 2 and 3 of the HLA-G gene. Mean sHLA-G levels in individuals with the most common HLA-G alleles G*01011 (27.0+/-2.1 SEM ng/ml, n=66), G*01012 (28.4+/-3.2 SEM ng/ml, n=34) were very similar. In contrast, individuals carrying the HLA-G*01013 (8.1+/-1.7 SEM ng/ml, n=17) or the "null" allele HLA-G*0105N (8.2+/-3.2 SEM ng/ml, n=7) presented significantly (P(c)=0.001 and P(c)<0.01, resp.) reduced sHLA-G levels. Furthermore, individuals with the HLA-G*01041 allele had significantly (P(c)=0.004) increased sHLA-G levels (42.5+/-4.6 SEM ng/ml, n=14). These results demonstrate that the generation of sHLA-G molecules is associated to certain HLA-G alleles and imply that sHLA-G levels are under genetic control. As low and high sHLA-G plasma levels did not segregate with HLA haplotypes including the HLA-G*01013 or *01041 allele, additional mechanisms may be involved in the regulation of the individual sHLA-G levels. Nevertheless, the existence of "low" and "high secretor" HLA-G alleles further suggests different levels of functionality in immune regulation.

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ABSTRACT

BACKGROUND The nonclassic human major histocompatibility complex class I antigens human leukocyte antigen (HLA)–G are proposed to protect tumor cells from natural killer cell lysis. In the current study, the authors measured soluble HLA‐G molecules (sHLA‐G) in serum from patients with malignant melanoma. METHODS Soluble HLA‐G was determined in serum samples of 190 melanoma patients with various stages of disease, with or without current therapy including interferon (IFN)–α and different cytostatics in comparison to 126 healthy controls by using a two‐step enzyme‐linked immunoadsorbent assay. RESULTS Serum sHLA‐G was significantly (P < 0.0005) elevated in melanoma patients (mean ± standard error of the mean [SEM] = 41.95 ± 2.15 ng/mL) compared with healthy controls (mean ± SEM = 22.92 ± 1.51 ng/mL). Univariate analysis revealed a correlation of sHLA‐G serum level with advanced stages of disease (P < 0.001) and tumor load (P < 0.05). Patients undergoing immunotherapy with IFN‐α (n = 31) showed an increased serum sHLA‐G (mean ± SEM = 62.05 ± 7.58 ng/mL; P < 0.0005), whereas other treatment regimens (n = 24) did not influence sHLA‐G serum concentrations. Multivariate analysis revealed treatment with IFN‐α as the only impact factor for elevated serum sHLA‐G, lacking any correlation with stage of disease or tumor burden. Furthermore, IFN‐α was found to upregulate HLA‐G cell surface expression on circulating monocytes. sHLA‐G serum level was not associated with recurrence free or overall survival. CONCLUSIONS This study shows increased sHLA‐G serum concentrations in melanoma patients and additional enhancement upon treatment with IFN‐α. The level of serum sHLA‐G, however, had no negative impact on patients' prognosis. Cancer 2001;92:369–76. © 2001 American Cancer Society.