The expression of HLA class I antigens in testicular germ cell tumors (TGCTs) was studied by the immunoperoxidase technique. In the normal testicle, the interstitial cells of Leydig as well as most of the germ cells were significantly stained. In typical seminoma, 75% of the tumor cells in stage I and 30% in stage II were stained. In embryonal cell carcinoma, 25% of the cases in stage I and less than 10% of those in stage II were stained. Mature teratoma was stained in most of the cases, whereas in malignant teratoma only 35% of the cases showed some staining of the tumor cells. In mixed tumors each component displayed its characteristic staining pattern. The expression of class I antigens on tumor cells is required for immune recognition and lysis of the tumor by cytotoxic T-cells. The reduced expression of class I antigens that was related to histologic characteristics and stage suggests that some testicular tumors may escape immune surveillance and become biologically more aggressive.
The binding of human lupus anti-DNA antibodies and murine anti-mycobacterial antibodies to human cortical brain tissue sections was assessed by the indirect immunofluorescent technique. Prior adsorption of the reactive monoclonal antibodies on nuclear extracts, ss-DNA, synthetic polynucleotide polymers, histones, mycobacterial glycolipids, and bovine brain extracts abrogated the monoclonal antibodies' binding to the brain. Intermediate blocking activity was conferred also by ribonucleic components as RNP, Ro(SSA), and La(SSB). Specificity to neuronal tissue was demonstrated by failure of non-neuronal tissue extracts to abolish antibodies' reaction to the cortical tissue sections in competition assays. The anti-TB and anti-DNA antibodies seemed to compete on their binding to a common neuronal membranal epitope. These results indicate that mycobacteria share antigens with DNA and human brain tissue. Furthermore, these data support the concept that anti-DNA antibodies may play a pathogenetic role in SLE patients with neuropsychiatric involvement via crossing of a "leaky" blood brain barrier and attachment to brain tissue components.
Sixty-seven patients on treatment with procainamide were examined for the presence of two common idiotypes of anti-DNA antibodies (16/6 Id and 32/15 Id). These idiotypes have been shown previously to have clinical relevance in patients with systemic lupus erythematosus (SLE). An enzyme-linked immunosorbent assay (ELISA) with rabbit anti-Id antibodies revealed increased concentrations of the 16/6 Id and 32/15 Id in 25 (37%) and 16 (24%) patients, respectively. Five of eight patients with drug-induced lupus had elevated titers of both idiotypes. A high correlation (R = 0.56, P less than 0.001 for 16/6 Id) was found between Id levels and anti-single-stranded DNA (ssDNA) antibody titers and between 16/6 Id titers and antihistone antibodies (IgG, R = 0.43; IgM, R = 0.25). It seems that procainamide, a component known to be associated with drug-induced lupus, may induce an increased production of common anti-DNA idiotypes in apparently normal subjects.
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