Results  When compared to the

post-partum samples, significant pregnancy-related changes in IFNγ, TNFα, VEGF, GCSF, Eotaxin, and MCP-1 expression were observed. These changes have significant immunologic effects in vivo and in culture. Conclusion  Pregnancy-associated changes to steady state serum cytokines may have important immunologic consequence. “
“We studied early NK-cell recovery in 29 allografted patients undergoing different lymphoreductive regimens. Already at 2 wk after graft take, the number of NK cells had find more reached (supra)normal levels but NK-cell subsets were skewed. The number of CD56dimCD16bright NK cells was low and correlated strongly with the level of hematopoiesis, whereas the number of the more abundant NK cells expressing high levels of CD56 did not. Post-transplant CD56bright NK cells (ptCD56bright) differed from CD56bright NK cells in normal controls (CD56bright) in being HLA-DR- and perforin-positive, CCR7−, CD27−, CD127− and mostly

c-kit−. CD56bright from normal controls stimulated by IL-15 in vitro (NKIL-15) acquired all the characteristics see more distinguishing CD56bright from ptCD56bright. IL-2 exerted similar effects. Moreover, when cultured without cytokines, ptCD56bright, CD56bright and NKIL-15 responded similarly by upregulating CD127 and c-kit but not CCR7. IL-12 stimulated IFN-γ production in ptCD56bright, whereas CD56bright responded only to IL-12 plus IL-15. Hence, ptCD56bright have all the features of cytokine-stimulated CD56bright. Because only patients with low numbers of T cells had high numbers of ptCD56bright, we conclude that ptCD56bright are activated CD56bright that expand while competing with T cells for the elevated post-transplant level of IL-15. In humans, most lymphocytes without those rearranged antigen-receptors express CD56 and are referred to as NK cells. Accordingly, they can be identified on the basis of a CD3−CD56+ phenotype 1–3, which excludes the subpopulation of T cells that coexpress CD56. However, this long-established definition of NK cells may be inadequate because CD3−CD56+ lymphocytes

are heterogeneous and capable of exerting various effector functions other than killing cells with altered expression of self-MHC. Furthermore, many CD3−CD56+ lymphocytes do not lyse NK-cell targets when tested ex vivo and only acquire lytic activity after in vitro stimulation with cytokines. In fact, the large granular CD3−CD56+ lymphocytes with “natural” cytotoxicity that express low levels of CD56 (CD56dim) and high levels of the Fcγ-receptor type III (CD16) 1–4 represent only a minority of all of the CD3−CD56+ lymphocytes in the body 5, 6. CD56dim that provide first-line defense against viruses 7, 8 make out 90% of NK cells in human peripheral blood. They express killer immunoglobulin-like receptors (KIR), contain perforin and granzymes and are considered to be end-stage cytotoxic effector cells. A substantial percentage of CD56dim lacks CD94 4.