CD49d Treg cells with high suppressive capacity are remarkably less efficient on activated CD45RA- than on naive CD45RA+ Teff cells.

BACKGROUND: Impairment of regulatory T cells (Tregs) in common autoimmune diseases seems likely. However, the extent of Treg deficiency (number, function) or differential susceptibility of T effector cells (Teffs) to suppression is not completely understood. We hypothesize that even in healthy individuals both cell populations are heterogeneous and differ in their suppressive capability and their susceptibility to suppression. MATERIAL AND METHODS: Lymphocytes were enriched by MACS for CD4(+)CD25(+) Tregs or CD4(+)CD25(-) Teffs. After multicolour staining (anti-CD25, anti-CD127, anti-CD49d or anti-CD45RA) highly purified Treg and Teff subpopulations were collected by FACS. Functional capacity of Tregs or suppressive susceptibility of Teffs was analyzed in an in vitro assay. RESULTS: When CD4(+)CD25(high)CD127(-/low) CD49d(-) Tregs were tested on naive CD4(+)CD127(+)CD25(-)CD45RA(+) Teffs (93.8 %) suppression was almost complete, while the suppressive capacity of CD4(+)CD25(high)CD127(-/low) CD49d(+) Tregs was significantly less (71.8 %). Suppressive activity was low when CD4(+)CD25(high)CD127(-/low) CD49d(+) Tregs were analyzed on CD4(+)CD127(+)CD25(-)CD45RA(-) Teffs (48.7%). CONCLUSION: Although CD49d(+) Tregs are functional, the suppressive capacity is significantly lower compared to CD49d(-) Tregs. CD45RA(+) Teffs can be completely suppressed, while CD45RA(-) Teffs display relative resistance. Phenotypic and functional heterogeneity of Tregs as well as Teffs has to be considered when analyzing deficiencies in immune regulation.

Indirect exclusion of four candidate genes for generalized progressive retinal atrophy in several breeds of dogs.

BACKGROUND: Generalized progressive retinal atrophy (gPRA) is a hereditary ocular disorder with progressive photoreceptor degeneration in dogs. Four retina-specific genes, ATP binding cassette transporter retina (ABCA4), connexin 36 (CX36), c-mer tyrosin kinase receptor (MERTK) and photoreceptor cell retinol dehydrogenase (RDH12) were investigated in order to identify mutations leading to autosomal recessive (ar) gPRA in 29 breeds of dogs. RESULTS: Mutation screening was performed initially by PCR and single strand conformation polymorphism (SSCP) analysis, representing a simple method with comparatively high reliability for identification of sequence variations in many samples. Conspicuous banding patterns were analyzed via sequence analyses in order to detect the underlying nucleotide variations. No pathogenetically relevant mutations were detected in the genes ABCA4, CX36, MERTK and RDH12 in 71 affected dogs of 29 breeds. Yet 30 new sequence variations were identified, both, in the coding regions and intronic sequences. Many of the sequence variations were in heterozygous state in affected dogs. CONCLUSION: Based on the ar transmittance of gPRA in the breeds investigated, informative sequence variations provide evidence allowing indirect exclusion of pathogenetic mutations in the genes ABCA4 (for 9 breeds), CX36 (for 12 breeds), MERTK (for all 29 breeds) and RDH12 (for 9 breeds).