Natural Killer Cell Lytic Granule Secretion Occurs through a Pervasive Actin Network at the Immune Synapse

Super-resolution imaging provides a new look at how the lytic granules in natural killer cells penetrate the filamentous actin network of the immunological synapse

Biallelic loss-of-function mutation in NIK causes a primary immunodeficiency with multifaceted aberrant lymphoid immunity

Primary immunodeficiency disorders enable identification of genes with crucial roles in the human immune system. Here we study patients suffering from recurrent bacterial, viral and Cryptosporidium infections, and identify a biallelic mutation in the MAP3K14 gene encoding NIK (NF- B-inducing kinase). Loss of kinase activity of mutant NIK, predicted by in silico analysis and confirmed by functional assays, leads to defective activation of both canonical and non-canonical NF- B signalling. Patients with mutated NIK exhibit B-cell lymphopenia, decreased frequencies of class-switched memory B cells and hypogammaglobulinemia due to impaired B-cell survival, and impaired ICOSL expression. Although overall T-cell numbers are normal, both follicular helper and memory T cells are perturbed. Natural killer (NK) cells are decreased and exhibit defective activation, leading to impaired formation of NK-cell immunological synapses. Collectively, our data illustrate the non-redundant role for NIK in human immune responses, demonstrating that loss-of-function mutations in NIK can cause multiple aberrations of lymphoid immunity

CD2 Promotes Human Natural Killer Cell Membrane Nanotube Formation

<div><p>Membrane nanotubes are thin membranous projections that physically connect two cells. While nanotubes have been studied in human natural killer (NK) cells and are implicated in aiding NK cell cytotoxic function, requirements for their formation to susceptible target cells remain incompletely understood. Here we demonstrate that the CD2-CD58/48 receptor-ligand interaction promotes and is required for nanotube formation in human NK cells. In the CD2⁻ NK cell line YTS, a stable CD2 expression variant enabled effective nanotube formation, and was associated with better cytotoxic function. Importantly, only interactions between an NK cell and a susceptible target cell were associated with multiple nanotubes and the number of nanotubes was inversely correlated with their length. Quantitative live cell fluorescence microscopy of CD2 nanotubes revealed time-dependent enrichment and localization of CD2 to the nanotube tip, and blocking CD2 receptor-ligand interactions prevented nanotube formation. Increased nanotube formation was not simply a feature of receptor-ligand pairing, as a KIR-MHC interaction in the same cell line system failed to promote nanotube formation. Additionally, blocking LFA-1-ICAM and 2B4-CD48 receptor-ligand interactions failed to inhibit nanotube formation. Thus only specific receptor-ligand pairs promote nanotubes. CD2 also promoted nanotube formation in <em>ex vivo</em> NK cells suggesting that CD2 plays a crucial role in the generation of nanotubes between an NK cell and its target.</p> </div

Correction: IFN-γ and IL-21 Double Producing T Cells Are Bcl6-Independent and Survive into the Memory Phase in Plasmodium chabaudi Infection.

[This corrects the article DOI: 10.1371/journal.pone.0144654.]

CD2 receptor-ligand interactions promote NT formation in eNK cells.

<p>(A) NTs were visualized in PKH26 labeled eNK cells isolated from whole blood. (B) eNK cells were labeled with PKH26, treated with isotype or anti-CD2 blocking antibody for 15 minutes, then incubated with 721 cells on anti-CD48 coated plates for 30 minutes. Single images were obtained to determine NT frequency (n>850 cells). (C) eNK cells were sorted into CD2⁺ and CD2⁻ populations using a non-blocking antibody to CD2. (D) CD2⁺ and CD2⁻ eNK populations were labeled with PKH26, and single images were obtained to determine the frequency of NK-NK (black bar) and NK-TC (grey bar) NT formation (n>325 cells). (Scale bar: 5 µm.).</p