Complete arrest from pro- to pre-B cells in a case of B cell-negative severe combined immunodeficiency (SCID) without recombinase activating gene (RAG) mutations

The B-cell lineage in a patient with B-cell-negative severe combined immunodeficiency (SCID) was analysed by using antisurrogate light chain (SL) MoAbs. Peripheral CD3+ T cells and CD19+ B cells were absent in the patient. The common gamma (γc) chain was expressed normally on the patient's peripheral NK cells and his peripheral mononuclear cells did not possess any mutations in recombinase activating gene (RAG)-1, 2. Normal levels of expression of Ku70 and Ku80 protein were found by Western blot analysis. The patient did, however, display an increase in fibroblast sensitivity to irradiation. Furthermore, flow cytometric analyses of bone marrow cells showed that surface IgM and cytoplasmic µ positive cells were absent and that CD19+ B cells were composed of only CD34+ terminal deoxynucleotidyl transferase (TdT)+ SL+ pro-B cells. The complete arrest of pro- to pre-B cell development in the SCID patient's bone marrow suggests that some genes involved in V(D)J recombination, excepting the RAG gene, may play a causative role in the immunodeficiency

Mechanisms of neuronal chloride accumulation in intact mouse olfactory epithelium

When olfactory receptor neurons respond to odours, a depolarizing Cl− efflux is a substantial part of the response. This requires that the resting neuron accumulate Cl− against an electrochemical gradient. In isolated olfactory receptor neurons, the Na+–K+–2Cl− cotransporter NKCC1 is essential for Cl− accumulation. However, in intact epithelium, a robust electrical olfactory response persists in mice lacking NKCC1. This response is largely due to a neuronal Cl− efflux. It thus appears that NKCC1 is an important part of a more complex system of Cl− accumulation. To identify the remaining transport proteins, we first screened by RT-PCR for 21 Cl− transporters in mouse nasal tissue containing olfactory mucosa. For most of the Cl− transporters, the presence of mRNA was demonstrated. We also investigated the effects of pharmacological block or genetic ablation of Cl− transporters on the olfactory field potential, the electroolfactogram (EOG). Mice lacking the common Cl−/HCO3− exchanger AE2 had normal EOGs. Block of NKCC cotransport with bumetanide reduced the EOG in epithelia from wild-type mice but had no effect in mice lacking NKCC1. Hydrochlorothiazide, a blocker of the Na+–Cl− cotransporter, had only a small effect. DIDS, a blocker of some KCC cotransporters and Cl−/HCO3− exchangers, reduced the EOG in epithelia from both wild-type and NKCC1 knockout mice. A combination of bumetanide and DIDS decreased the response more than either drug alone. However, no combination of drugs completely abolished the Cl− component of the response. These results support the involvement of both NKCC1 and one or more DIDS-sensitive transporters in Cl− accumulation in olfactory receptor neurons

FRET Based Quantification and Screening Technology Platform for the Interactions of Leukocyte Function-Associated Antigen-1 (LFA-1) with InterCellular Adhesion Molecule-1 (ICAM-1)

<div><p>The interaction between leukocyte function-associated antigen-1(LFA-1) and intercellular adhesion molecule-1 (ICAM-1) plays a pivotal role in cellular adhesion including the extravasation and inflammatory response of leukocytes, and also in the formation of immunological synapse. However, irregular expressions of LFA-1 or ICAM-1 or both may lead to autoimmune diseases, metastasis cancer, etc. Thus, the LFA-1/ICAM-1 interaction may serve as a potential therapeutic target for the treatment of these diseases. Here, we developed one simple ‘in solution’ steady state fluorescence resonance energy transfer (FRET) technique to obtain the dissociation constant (K_d) of the interaction between LFA-1 and ICAM-1. Moreover, we developed the assay into a screening platform to identify peptides and small molecules that inhibit the LFA-1/ICAM-1 interaction. For the FRET pair, we used Alexa Fluor 488-LFA-1 conjugate as donor and Alexa Fluor 555-human recombinant ICAM-1 (D1-D2-Fc) as acceptor. From our quantitative FRET analysis, the K_d between LFA-1 and D1-D2-Fc was determined to be 17.93±1.34 nM. Both the K_d determination and screening assay were performed in a 96-well plate platform, providing the opportunity to develop it into a high-throughput assay. This is the first reported work which applies FRET based technique to determine K_d as well as classifying inhibitors of the LFA-1/ICAM-1 interaction.</p></div