J.Y. Sun

The Effect of Single and Combined Activating Killer Immunoglobulin-like Receptor Genotypes on Cytomegalovirus Infection and Immunity after Hematopoietic Cell Transplantation

It has been shown that activating killer Ig-like receptor (aKIR) genes are important for control of cytomegalovirus (CMV) reactivation after hematopoietic cell transplantation (HCT). To date, using the broad classification of KIR haplotypes A and B, the precise role of individual KIR genes in the control of infection cannot be discerned. To address this, a consecutive case series of 211 non-T cell-depleted HCT patients all at risk for CMV were monitored biweekly for CMV DNA in plasma by quantitative polymerase chain reaction (Q-PCR) and at intervals for CMV-specific T cell immunity. Comparing patients with CMV reactivation (n = 152) to those with no reactivation (n = 59), the presence of specific aKIR haplotypes in the donor, but not in the recipient, were associated with protection from CMV reactivation and control of peak plasma CMV DNA (P < .001). A donor aKIR profile, predictive for low risk of CMV reactivation, contained either aKIR2DS2 and aKIR2DS4 or had >/=5 aKIR genes. Neither donor nor recipient inhibitory KIR (iKIR) played a role in a protective effect. CD4(+)- and CD8(+)-specific CMV immunity did not explain reduced CMV infection. The initial control of CMV infection after HCT is managed by aKIR functions, and donor aKIR haplotypes deserve further evaluation in donor selection for optimized HCT outcome.

Impact of Graft Cell Dose on Transplant Outcomes following Unrelated Donor Allogeneic Peripheral Blood Stem Cell Transplantation: Higher CD34+ Cell Doses Are Associated with Decreased Relapse Rates

Peripheral blood stem cells (PBSC) have been increasingly used in the matched unrelated donor (MUD) transplant setting, but the impact of CD34(+) cell dose on outcomes in this setting have not been well characterized. We analyzed 181 consecutive patients who underwent MUD-PBSC transplantation at the City of Hope between August 2000 to December 2004. Patients were conditioned with either full-intensity regimen or reduced-intensity regimen. There was a significant inverse relationship between higher CD34(+) cell dose and faster neutrophil engraftment (r = -0.16, P = .035). By univariate analysis, a CD34(+) cell dose > or =4.2 x 10(6)/kg (above the lowest quartile) was associated with significantly lower relapse risk (hazard ratio [HR] = 0.67, P = .0126), with a trend for corresponding improvement for disease-free survival (HR = 0.84, P = .12) but not overall survival (HR = 0.91, P = .46). The impact of the CD34(+) cell dose remained significant in multivariate analysis. The higher CD34(+) cell dose was significantly associated with faster recovery of absolute lymphocyte counts on day +30 posttransplant. Subset analysis demonstrated that the higher CD34(+) cell dose was associated with (1) greater reduction in relapse in myeloid malignancies than that in lymphoid malignancies, (2) greater reduction in reduced-intensity conditioning than in full-intensity conditioning, (3) greater reduction in relapse when there is a inhibitory killer-cell immunoglobulin-like receptor ligand (iKIRL)-mismatch in the gravft-versus-host (GVH) direction, and (4) greater reduction in relapse when there is a lack of iKIRL, suggesting that the protective effect of CD34(+) cell dose against relapse may be immune-mediated, possibly through NK cell recovery.

Lack of KIR2DL4 gene in a fertile Caucasian woman

Killer cell immunoglobulin-like receptor (KIR2DL4) gene is present in virtually all humans. It encodes a receptor present on uterine and decidual natural killer (NK) cells and some peripheral blood NK cells. Its only known ligand is human leukocyte antigen-G molecule expressed on extravillous trophoblasts invading the decidua. Therefore, KIR2DL4 has been regarded as a molecule important for successful pregnancy. However, a multiparous woman from Africa, lacking KIR2DL4 gene, was described suggesting that this gene is not absolutely required for successful human reproduction. Here, we describe a Polish woman who delivered a child and who is not only lacking KIR2DL4 gene, but also possessing a KIR genotype virtually identical to that of the African woman mentioned above. Their genotypes are compared with few other KIR2DL4-negative genotypes and haplotypes described so far.

Alleles and intron polymorphism of KIR3DL1 shown by combination of allele group-specific primers and sequencing.

Allelic polymorphism of killer immunoglobulin-like receptor (KIR) genes may affect receptor expression as well as function. We used a combination of allele group-specific primers and DNA sequencing techniques to verify our KIR genotyping primers in polymerase chain reaction and identified three KIR3DL1 alleles. By sequencing some introns of 3DL1 in 18 genomic DNA samples, we found that a 4-bp insert in intron 1 of 3DL1*002 exists in multiple alleles, but that a 2-bp deletion in intron 7 is unique to 3DL1*01501 and that a 19-bp insert in intron 1 seems specific to the CEPH family 1416. Our data suggest that extensive KIR gene polymorphisms are ubiquitous as well as quite complex.