Leucocyte beta 1,3 galactosyltransferase activity in IgA nephropathy

BACKGROUND: Reduced galactosylation of the O-linked glycans of the IgA1 hinge region in IgAN has recently been described. To investigate the underlying defect resulting in this abnormality, we have measured the activity of beta 1,3 galactosyltransferase, the enzyme responsible for galactosylation of O-linked sugars. METHODS: A galactose-acceptor substrate was prepared from degalactosylated hinge region fragments of normal IgA1, and incubated with the T cell, B cell, and monocyte lysates from patients with IgAN and controls for acceptor regalactosylation. The extent of acceptor galactosylation was then measured with biotinylated Vicia villosa lectin (VV), which is specific for ungalactosylated moieties. Lectin binding of serum IgA from the same subjects was also measured. RESULTS: T cell and monocyte beta 1,3 galactosyltransferase activities did not differ between IgAN and control, but B cell lysates in IgAN showed significantly lower beta 1,3 galactosyltransferase activity than control (6.2 +/- 0.71 vs. 9.5 +/- 1.03 AU/microgram, P = 0.018). Furthermore, B cell beta 1,3 galactosyltransferase activity showed a negative correlation (r = - 0.87, P = 0.002) with VV lectin binding of serum IgA in IgAN, but not controls. CONCLUSIONS: These data indicate that altered IgA1 O- galactosylation in IgAN results from a B cell-restricted reduction of beta 1,3 galactosyltransferase activity. This enzyme defect may be a fundamental pathogenic abnormality in IgAN.      

An unusual consequence of stereotactic colloid cyst aspiration: Case report

The removal of a colloid cyst of the third ventricle by stereotactic cyst aspiration is frequently performed as an alternative to a transcortical-transventricular or transcallosal operative route. A consequence of a CT-guided stereotactic aspiration, where residual colloid cyst material has been dislodged into the lateral ventricle and likened to an intraventricular mouse, is described.     

Persistent cutaneous pseudolymphoma after intradermal gold injection

After intradermal testing with goldsodiumthiomalate (GSTM), 5 out of 8 patients developed skin papules at the test sites, which persisted up to 20 months. The lesions were surgically excised. Histology revealed pseudolymphoma of B and T cell type containing follicular structures and occasional small granulomas. The amount of histiocytic cells among B and T lymphocytes was pronounced, including acid cysteine proteinase inhibitor (ACPI) positive follicular dendritic cells, CD68 positive macrophages, factor XUIa positive dermal dendrocytes and S-100 positive cells. By electron microscopy, the macrophages contained endosomes loaded with crystalloid material which contained gold in X-ray microanalysis. Atomic absorption spectrophotometry also confirmed the presence of gold in one specimen. Thus GSTM seemed to accumulate in tissue macrophages leading to constant immunologic activation with lymphoid proliferation and histiocytic response.     

HLA-DRB1 in eight Finnish monozygotic twin pairs concordant for rheumatoid arthritis

This study presents the results of HLA-DRB1 typing of the eight monozygotic twin pairs with both members affected by rheumatoid arthritis (RA), sampled in the nationwide Finnish twin cohort. The shared epitope, associated with RA in case-control studies, was present in all eight twin pairs, being significantly more frequent than among RA patients in a recent Dutch case-control study. Furthermore, 4 out of 8 twin pairs were homozygous for the shared epitope, while in 73 Dutch healthy controls encoding the shared epitope only 13 (18%) were homozygous; this suggests a gene dose effect in RA susceptibility. Combining these results with data from other sources may help to clarify the contribution of HLA alleles in the genetic predisposition to RA.