Stabilization of white blood cells and immunologic markers for extended analysis using flow cytometry

We evaluated whole blood samples drawn from 25 healthy donors and 20 HIV-infected donors into K3EDTA and Cyto-Chex BCT blood collection tubes for CD4, CD8, and CD3 cell counts (HIV Panel). Samples collected in Cyto-Chex BCT were stored at room temperature and tested by 4-color flow cytometry at 6 h, 3 days, and 7 days after isolation for CD4, CD8, and CD3 absolute cell counts/microl and compared with samples collected in K3EDTA tubes and tested at 6 h. Regardless of donor type, the samples collected in Cyto-Chex BCT and tested on day 7 yielded results that were statistically indistinguishable (with correlation coefficients of 0.96 or greater) from samples collected in K3EDTA tubes and tested at 6 h. We conclude that whole blood samples collected in Cyto-Chex BCT are stabilized for their marker phenotype for at least 7 days after phlebotomy.

Human Papillomavirus L1L2-E7 Virus-Like Particles Partially Mature Human Dendritic Cells and Elicit E7-Specific T-Helper Responses From Patients With Cervical Intraepithelial Neoplasia or Cervical Cancer In Vitro

We evaluated the ability of autologous dendritic cells (DC) pulsed with recombinant human papillomavirus 16 L1L2-E7 virus-like particles (VLPs) to stimulate E7-specific CD4+ T-cell responses from normal donors and patients with cervical intraepithelial neoplasia lesions or cervical carcinoma in vitro. Exposure to VLPs partially matured DCs, as evidenced by upregulated expression of costimulatory and major histocompatibility complex molecules and the reduced capacity of treated DCs to process exogenous antigens. However, VLP treatment failed to promote strong expression of the CD83 or CCR7 markers or to modulate interleukin-12p70 secretion, indicators of terminal DC maturation. Notably, both normal donor- and patient-derived DCs behaved similarly after exposure to VLPs. A single round of in vitro stimulation of CD4+ T cells with DCs exposed to L1L2-E7 VLPs promoted specific anti-E7 responses in the majority of donors. In particular, DCs exposed to VLPs effectively stimulated type 1 biased E7-specific CD4+ T-cell responses in patients with premalignant cervical intraepithelial neoplasia I-III lesions, but type 2 or Treg biased responses in patients with cervical cancer. Given the high rate of CD4+ T-cell responses (14 [93%] of 15 patients) against DC-L1L2-E7 VLP stimulation, this vaccine modality could serve as a foundation for developing a general treatment option for patients with human papillomavirus 16-associated malignancies.

Disease-stage variance in functional CD4(+) T-cell responses against novel pan-human leukocyte antigen-D region presented human papillomavirus-16 E7 epitopes

Given the anticipated clinical importance of helper and regulatory CD4(+) T cells reactive against human papillomavirus-16 E7 in the cervical carcinoma setting, we performed this study to identify novel E7-derived T helper (Th) epitopes and to characterize functional anti-E7 Th responses in normal donors and patients with cervical intraepithelial neoplasia I-III or cervical cancer. Candidate pan-HLA-DR (D region) binding peptides were identified and synthesized based on results obtained using a predictive computer algorithm, then applied in short-term in vitro T-cell sensitization assays. Using IFN-gamma/IL-5 (interleukin 5) enzyme-linked immunospot assays as readouts for Th1-type and Th2-type CD4(+) T-cell responses, respectively, we identified three E7-derived T helper epitopes (E7(1-12), E7(48-62), and E7(62-75)), two of which are novel. Normal donor CD4(+) T cells failed to react against these E7 peptides, whereas patients with premalignant cervical intraepithelial neoplasia I-III lesions displayed preferential Th1-type responses against all three E7 epitopes. Th1-type responses were still observed to the E7(48-62) but not to the E7(1-12) and E7(62-75) peptides in cancer patients, where these latter two epitopes evoked Th2-type responses. Notably all responders to the E7(1-12) and E7(62-75) peptides expressed the HLA-DR4 or -DR15 alleles, whereas all responders to the E7(48-62) peptide failed to express the HLA-DR4 allele. Our results are consistent with a model in which cervical cancer progression is linked to an undesirable Th1- to Th2-type shift in functional CD4(+) T cell responses to two novel E7-derived epitopes. These peptides may prove important in vaccines to promote and maintain protective Th1-type antihuman papillomavirus immunity and in the immune monitoring of treated patients harboring HPV-16(+) malignancies.