Natural killer cell number and phenotype in bovine peripheral blood is influenced by age

Natural killer (NK) cells are critical to the innate defence against intracellular infection. High NK cell frequencies have been detected in human neonates, which may compensate for the relative immaturity of the specific immune response. Additionally, phenotypic subsets of NK cells have been identified in humans with different functional properties. In this study, we examined the age distribution and phenotype of NK populations in bovine peripheral blood, including neonatal animals. We found that the NK cell populations defined by the phenotypes CD3<sup>−</sup>CD2<sup>+</sup> and NKp46<sup>+</sup> largely overlapped, so that the majority of NK cells in bovine peripheral blood were CD3−CD2<sup>+</sup>NKp46<sup>+</sup>. The remainder of the NK-like cells comprised two minor populations, CD3<sup>−</sup>CD2<sup>+</sup>NKp46<sup>−</sup> and CD3<sup>−</sup>CD2<sup>−</sup>NKp46<sup>+</sup>; the relative proportions of these varied with age. The lowest frequency of NK cells was recorded in 1-day-old calves, with the highest frequency in day 0 calves. The phenotypic characteristics of CD3<sup>−</sup>CD2<sup>+</sup> and NKp46<sup>+</sup> NK populations were similar; both populations expressed CD45RO, CD45RB, CD11b, CC84, CD8αα and CD8αβ and did not express CD21, WC1, CD14 or γδ TCR. Age-related phenotypic differences were apparent. The phenotypic characteristics of three NK subpopulations were described; a significantly greater proportion of the CD3<sup>−</sup>CD2<sup>−</sup>NKp46<sup>+</sup> population expressed CD8α compared to CD3<sup>−</sup>CD2<sup>+</sup>NKp46<sup>+</sup> cells. Furthermore, a significantly greater proportion of the CD3<sup>−</sup>CD2<sup>+</sup>NKp46<sup>−</sup> population expressed CD8 compared to total CD3<sup>−</sup>CD2<sup>+</sup> cells. Adult cattle had a significantly higher proportion of perforin+ cells compared to calves aged ≤6 weeks. In this age group, the majority of perforin+ cells expressed NKp46, while in adults the majority of perforin<sup>+</sup> cells were NKp46<sup>−</sup>. However, the proportion of NKp46<sup>+</sup> and CD3<sup>−</sup>CD2<sup>+</sup> cells that expressed perforin was not significantly different in any age group tested

Infecção experimental em cabritos pelo vírus da artrite encefalite Caprine arthritis encephalitis virus experimental infection in new-born kids

Vinte e quatro caprinos de uma semana de idade, soronegativos pela imunodifusão em gel de agar para artrite encefalite caprina (AEC), foram utilizados para estudo de infecção experimental pelo vírus da AEC. Dezesseis animais foram inoculados com lentivirus caprino, amostra Cork, oito pela via intravenosa e oito por instilação nasal. Oito animais serviram como controle, inoculados pelas vias intranasal ou intravenosa com 1ml de meio de cultura de células não infectadas. Os animais foram sacrificados aos 2, 6, 12 e 20 dias pós-inoculação (PI), e colhidas amostras do sistema nervoso central, articulações, tonsilas, linfonodos, pulmões, rins, timo, baço e intestinos delgado e grosso para histopatologia e imunoistoquímica. Um animal inoculado com o vírus da AEC pela via intranasal e sacrificado aos 20 dias PI apresentou imunomarcação positiva em um macrófago alveolar. Concluiu-se que a via aerógena é uma provável rota de infecção pelo vírus da AEC.<br>The caprine arthritis encephalitis virus (CAEV) experimental infection was studied in 24 one-week-old seronegative kids. Sixteen kids were inoculated with CAEV-Cork, with 10(6) TCID50/ml concentration, being eight inoculated intravenously, and eight intranasally. Eight animals were used as controls, being four inoculated intravenously, and four intranasally with non-infected cell culture medium. Since the day of the inoculation, clinical evaluation was performed daily, until the day of the sacrifice. Blood samples were taken for serological tests. The animals were killed in pairs at 2, 6, 12 and 20 days post-inoculation (PI) and tissues samples of central nervous system, joints, tonsils, lymphonodes, lungs, kidneys, thymus, spleen, small and large intestine were collected for histopathological and immunohistochemical studies. One animal CAEV inoculated intranasally and killed at 20 days PI showed immunohistochemical positive reaction in an alveolar macrophage. It was concluded that transmission by air is a probable rote of CAEV infection

Speed and selection in the evolution of killer-cell immunoglobulin-like receptors

The killer-cell immunoglobulin-like receptors (KIR) form a diverse family of receptors that control the functions of natural killer cells. Sequencing of KIR from primates has revealed the unexpected extent to which this gene family has diversified mostly likely in response to pathogens and to pathogen-mediated selection of their MHC class I ligands. Human KIR diversity is now a burgeoning area for disease association studies. This review examines the evolution of KIR from a primate-centric view in order to rationalize our current knowledge of the diversity of human KIR