Cerebrospinal fluid anti-myelin antibodies are related to magnetic resonance measures of disease activity in multiple sclerosis.

OBJECTIVE: Recent studies reported contrasting results with respect to the presence of anti-myelin protein antibodies in multiple sclerosis (MS) and their relation with disease activity. This may be due to the heterogeneous specificity of autoantibodies in MS and the inability of most methods to detect pathogenically relevant antibodies. Here, myelin particles were used to detect anti-myelin antibodies in the CSF of MS patients. Subsequently, their relation with MRI parameters was evaluated. METHODS: Anti-myelin IgG antibody reactivity was determined in the CSF of patients with MS (n = 65) and clinically isolated syndrome (CIS, n = 37) using a novel flow cytometry based assay. In addition, the CSF of patients with other neurological diseases (OND, n = 17), inflammatory neurological diseases (IND, n = 33) and controls (n = 22) was tested. RESULTS: Compared with controls, increased anti-myelin IgG antibody reactivity was most frequently found in the CSF of patients with CIS (46%, p = 0.002), relapsing-remitting MS (56%, p<0.001) and secondary progressive MS (55%, p<0.001), together constituting 85% of all positive CSF samples. In contrast, elevated anti-myelin IgG antibody reactivity was present in a minority of IND patients (21%), marginally present in controls (5%) and absent in OND patients (0%). Most strikingly, anti-myelin IgG antibody reactivity was related to the number of T2 lesions (r = 0.31, p = 0.041) and gadolinium enhancing T1 lesions (r = 0.37, p = 0.016) on brain MRI in CIS and relapse onset MS patients. CONCLUSION: CSF anti-myelin IgG antibodies are promising specific biomarkers in CIS and relapse onset MS and correlate with MR measures of disease activity.

Osteopontin levels and increased disease activity in relapsing-remitting multiple sclerosis patients.

Osteopontin (OPN) has been identified as the most prominent cytokine-encoding gene expressed within multiple sclerosis (MS) lesions. Recently, we demonstrated that OPN plasma levels were elevated in active relapsing-remitting (RR) MS patients. In this longitudinal study, a trend was observed for OPN serum levels in relation to clinical exacerbations. Moreover, OPN protein levels were significantly elevated 1 month prior to increase of gadolinium (Gd)-enhancing lesion number, whereas no relation was observed between OPN levels and increase in Gd-enhancing lesion volume. Although no robust relation between OPN and disease activity was observed, these data suggest that OPN levels are elevated prior to increased disease activity in RR MS patients.

UTY gene codes for an HLA-B60-restricted human male-specific minor histocompatibility antigen involved in stem cell graft rejection: characterization of the critical polymorphic amino acid residues for T-cell recognition.

Rejection of a graft after human leukocyte antigen (HLA)-identical stem cell transplantation (SCT) can be caused by recipient's immunocompetent T lymphocytes recognizing minor histocompatibility antigens on donor stem cells. During rejection of a male stem cell graft by a female recipient, 2 male (H-Y)-specific cytotoxic T lymphocyte (CTL) clones were isolated from peripheral blood. One CTL clone recognized an HLA-A2-restricted H-Y antigen, encoded by the SMCY gene. Another CTL clone recognized an HLA-B60-restricted H-Y antigen. In this study UTY was identified as the gene coding for the HLA-B60-restricted H-Y antigen. The UTY-derived H-Y antigen was characterized as a 10-amino acid residue peptide, RESEEESVSL. Although the epitope differed by 3 amino acids from its X-homologue, UTX, only 2 polymorphisms were essential for recognition by the CTL clone HLA-B60 HY. These results illustrate that CTLs against several H-Y antigens derived from different proteins can contribute simultaneously to graft rejection after HLA-identical, sex-mismatched SCT. Moreover, RESEEESVSL-specific T cells could be isolated from a female HLA-B60+ patient with myelodysplastic syndrome who has been treated with multiple blood transfusions, but not from control healthy HLA-B60+ female donors. This may indicate that RESEEESVSL-reactive T cells are more common in sensitized patients.

DFFRY codes for a new human male-specific minor transplantation antigen involved in bone marrow graft rejection.

Graft rejection after histocompatibility locus antigen (HLA)-identical stem cell transplantation results from the recognition of minor histocompatibility antigens on donor stem cells by immunocompetent T lymphocytes of recipient origin. T-lymphocyte clones that specifically recognize H-Y epitopes on male target cells have been generated during graft rejection after sex-mismatched transplantation. Previously, 2 human H-Y epitopes derived from the same SMCY gene have been identified that were involved in bone marrow graft rejection. We report the identification of a new male-specific transplantation antigen encoded by the Y-chromosome-specific gene DFFRY. The DFFRY-derived peptide was recognized by an HLA-A1 restricted CTL clone, generated during graft rejection from a female patient with acute myeloid leukemia who rejected HLA-phenotypically identical bone marrow from her father. The identification of this gene demonstrates that at least 2 genes present on the human Y-chromosome code for male-specific transplantation antigens.

The importance of methylthio-IMP for methylmercaptopurine ribonucleoside (Me-MPR) cytotoxicity in Molt F4 human malignant T-lymphoblasts.

The importance of methyl-thioIMP (Me-tIMP) formation for methylmercaptopurine ribonucleoside (Me-MPR) cytotoxicity was studied in Molt F4 cells. Cytotoxicity of Me-MPR is caused by Me-tIMP formation with concomitant inhibition of purine de novo synthesis. Inhibition of purine de novo synthesis resulted in decreased purine nucleotide levels and enhanced 5-phosphoribosyl-1-pyrophosphate (PRPP) levels, with concurrent increased pyrimidine nucleotide levels. The Me-tIMP concentration increased proportionally with the concentration of Me-MPR. High Me-tIMP concentration also caused inhibition of PRPP synthesis. Maximal accumulation of PRPP thus occurred at low Me-MPR concentrations. As little as 0.2 microM Me-MPR resulted already after 2 h in maximal inhibition of formation of adenine and guanine nucleotides, caused by inhibition of purine de novo synthesis by Me-tIMP. Under these circumstances increased intracellular PRPP concentrations could be demonstrated, resulting in increased levels of pyrimidine nucleotides. So, in Molt F4 cells, formation of Me-tIMP from Me-MPR results in cytotoxicity by inhibition of purine de novo synthesis.