Expansion and enhanced survival of natural killer cells expressing the killer immunoglobulin-like receptor KIR3DL2 in spondylarthritis.

OBJECTIVE: The spondylarthritides (SpA) are strongly associated with possession of HLA-B27. We hypothesized that the expression of abnormal forms of HLA-B27 in SpA may have a pathogenic role through interaction with cells bearing natural killer (NK) receptors, in particular, killer immunoglobulin-like receptor (KIR) KIR3DL2, a receptor for HLA-B27 homodimer (B27(2)). We therefore undertook the present study to determine the number and function of NK and T cells bearing KIR3DL2 in SpA. METHODS: Expression of KIR3DL2 on NK and T cells was quantified in peripheral blood (PB) from 35 patients with SpA and 5 patients with juvenile enthesitis-related arthritis (juvenile ERA); samples were compared with samples from healthy and rheumatoid arthritis (RA) controls. Paired synovial fluid (SF) was studied where available. Expression of other KIRs as well as activation, memory, and homing markers on KIR3DL2+ NK and T cells was quantified. NK cell survival was assessed using the apoptotic markers annexin V and 7-aminoactinomycin D, and cytotoxicity by (51)Cr release assay. RESULTS: In SpA, an increased number of PB and SF NK and CD4+ T cells expressed the KIR3DL2 receptor compared with controls. In ERA, KIR3DL2 expression was increased in PB and SF CD4 T cells (and SF NK cells) compared with RA controls. KIR3DL2+ NK cells had an activated phenotype, and were protected from apoptosis by culture with a cell line expressing B27(2). SpA PB mononuclear NK cells from SpA patients showed greater cytotoxicity than those from controls. CONCLUSION: KIR3DL2 expression on NK cells and CD4 lymphocytes is increased in SpA and ERA. These cells are activated and may have a pathogenic role.

Identification of the principal serological immunodeterminants of African swine fever virus by screening a virus cDNA library with antibody.

Protective immunity to African swine fever virus (ASFV) may involve a combination of both serological and cellular mechanisms. This work is focused on the identification of the possible relevant serological immunodeterminants of immunity. Thus, 14 serological immunodeterminants of ASFV have been characterized by exhaustive screening of a representative lambda phage cDNA expression library of the tissue culture-adapted Ba71V strain of ASFV. The library was constructed using RNA extracted from Vero cells infected for 3, 6, 9 and 12 h. A total of 150 clones was selected arbitrarily by antibody screening of the library with a polyclonal antiserum from a domestic pig surviving infection with the virulent Malta isolate of ASFV. Sequencing of these clones permitted identification of 14 independent viral proteins that stimulated an antibody response. These included six proteins encoded by previously unassigned open reading frames (ORFs) (B602L, C44L, CP312R, E184L, K145R and K205R) as well as some of the more well-studied structural (A104R, p10, p32, p54 and p73) and non-structural proteins (RNA reductase, DNA ligase and thymidine kinase). Immunogenicity of these proteins was confirmed by demonstrating the corresponding antibodies in sera from pigs infected either with the Malta isolate or with the OURT88/3-OURT88/1 isolate combination. Furthermore, the majority of these ORFs were also recognized by immune antiserum from the natural host, the bush pig, following secondary challenge with the virulent Malawi (SINT90/1) isolate of ASFV. Thus, it is possible that some of these determinants may be important in protection against virus infection.