Marie Fuerst

Optimization of methods to assess human mucosal T-cell responses to HIV infection

The majority of HIV-1 infections occur via sexual transmission at mucosal epithelia lining the vagina, cervix or rectum. Mucosal tissues also serve as viral reservoirs. However, our knowledge of human mucosal T-cell responses is limited. There is a need for reliable, sensitive, and reproducible methods for assessing mucosal immunity. Here we report on the collaborative efforts of two laboratories to optimize methods for processing, culturing, and analyzing mucosal lymphocytes. Rectal biopsy tissue was obtained by flexible sigmoidoscopy, which is rapid, minimally invasive, and well tolerated. Of the four methods compared for isolating mucosal mononuclear cells (MMC), collagenase digestion reproducibly yielded the most lymphocytes (4-7 x 10(6)). Furthermore, 0.5-1 x 10(6) MMC could be polyclonally expanded to yield 17 x 10(6) CD8+ T cells allowing mapping of responses to overlapping peptides spanning the HIV-1 genome using IFN-gamma enzyme-linked immunospot (ELISpot). Expansion also reduced the spontaneous IFN-gamma production normally detected in fresh MMC. Piperacillin-tazobactam and amphotericin B reduced contamination of MMC cultures to 4%. Taken together, these methods will be useful for studies of mucosal immunity to HIV-1 and other pathogens during natural infection and following vaccination.

Increased HIV-1 mucosal replication is associated with generalized mucosal cytokine activation.

The purpose of this study was to characterize intestinal mucosal cytokine profiles in subjects with HIV-1 infection and their relation to mucosal viral load (MVL). Intestinal mucosal cytokine mRNA (interleukin [IL]-2, interferon [IFN]-γ, IL-12, IL-10, IL-1β, tumor necrosis factor [TNF]-α, IL-6, and regulated upon activation, normal T-cell expressed and secreted [RANTES]) and HIV-1 RNA were quantified using real-time polymerase chain reaction (PCR). On the basis of MVL quantification, the HIV-1–infected subjects were divided into 3 groups: undetectable MVL (<50 copies/μg of tissue total RNA), low MVL (>50 but <5000 copies/μg of tissue total RNA), and high MVL (>5000 copies/μg of tissue total RNA). Compared with the control group, significant reductions in RANTES, IL-2, and IFNγ expression were seen in the undetectable MVL group (P < 0.005). IL-6 was significantly increased in all the HIV groups (P < 0.005), and RANTES, IL-10, and IFNγ were increased in the high MVL group (P < 0.005). Subjects with high MVL have generalized immune activation with increases in T helper (Th)1, Th2, and proinflammatory cytokines, whereas subjects with undetectable MVL have reduced expression of multiple cytokines. The pathologic basis for these observations is unclear but may relate to the success or failure of antiretroviral therapy in controlling mucosal viral replication.

Parallel human immunodeficiency virus type 1-specific CD8(+) T-lymphocyte responses in blood and mucosa during chronic infection

ABSTRACT Gut-associated lymphoid tissue is the major reservoir of lymphocytes and human immunodeficiency virus type 1 (HIV-1) replication in vivo, yet little is known about HIV-1-specific CD8+ T-lymphocyte (CTL) responses in this compartment. Here we assessed the breadth and magnitude of HIV-1-specific CTL in the peripheral blood and sigmoid colon mucosa of infected subjects not on antiretroviral therapy by enzyme-linked immunospot analysis with 53 peptide pools spanning all viral proteins. Comparisons of blood and mucosal CTL revealed that the magnitude of pool-specific responses is correlated within each individual (mean r2 = 0.82 ± 0.04) and across all individuals (r2 = 0.75; P < 0.001). Overall, 85.1% of screened peptide pools yielded concordant negative or positive results between compartments. CTL targeting was also closely related between blood and mucosa, with Nef being the most highly targeted (mean of 2.4 spot-forming cells [SFC[/106 CD8+ T lymphocytes/amino acid [SFC/CD8/aa]), followed by Gag (1.5 SFC/CD8/aa). Finally, comparisons of peptide pool responses seen in both blood and mucosa (concordant positives) versus those seen only in one but not the other (discordant positives) showed that most discordant results were likely an artifact of responses being near the limit of detection. Overall, these results indicate that HIV-1-specific CTL responses in the blood mirror those seen in the mucosal compartment in natural chronic infection. For protective or immunotherapeutic vaccination, it will be important to determine whether immunity is elicited in the mucosa, which is a key site of initial infection and subsequent HIV-1 replication in vivo.

HIV-related diarrhea is multifactorial and fat malabsorption is commonly present, independent of HAART

OBJECTIVE:Highly active antiretroviral therapy (HAART) has significantly decreased the incidence of infectious diarrhea affecting HIV-infected patients. Still, diarrhea remains a common symptom in HIV. We sought to determine the incidence of fat malabsorption as a cause of diarrhea in HIV patients receiving non-HAART (nucleoside analog only) and HAART (protease inhibitor-containing) antiretroviral regimens.METHODS:From June, 1995, to April, 1999, 88 HIV-infected patients underwent evaluation for diarrhea, which included endoscopy. We examined the incidence of fat malabsorption with a 24-h stool collection for fecal fat in a cohort of these patients (N = 33). Patients were divided into two groups, those receiving protease inhibitor-containing HAART and those receiving less intensive, nucleoside analog-only, non-HAART regimens.RESULTS:Thirty of 33 patients (90.9%) had fat malabsorption. Twenty of 21 patients not receiving HAART (95.2%) had fat malabsorption with a mean of 34 ± 38 g of stool fat and a mean stool weight of 797 ± 454 g. Ten of 12 patients receiving HAART (83.3%) had fat malabsorption with a mean of 46 ± 86 g of stool fat and a mean stool weight of 800 ± 647 g. Stool weight correlated with the degree of fat malabsorption (R = 0.77).CONCLUSION:Fat malabsorption represents a commonly undiagnosed entity in HIV-infected patients with diarrhea, whether or not they are receiving HAART therapy. Fecal fat determination should be considered a routine part of the diagnostic workup of HIV-infected patients experiencing diarrhea.

Differential immunogenicity of vaccinia and HIV-1 components of a human recombinant vaccine in mucosal and blood compartments

Mucosal immune responses induced by HIV-1 vaccines are likely critical for prevention. We report a Phase 1 safety and immunogenicity trial in eight participants using the vaccinia-based TBC-3B vaccine given subcutaneously to determine the relationship between HIV-1 specific systemic and gastrointestinal mucosal responses. Across all subjects, detectable levels of blood vaccinia- and HIV-1-specific antibodies were elicited but none were seen mucosally. While the vaccinia component was immunogenic for CD8(+) T lymphocyte (CTL) responses in both blood and mucosa, it was greater in blood. The HIV-1 component of the vaccine was poorly immunogenic in both blood and mucosa. Although only eight volunteers were studied intensively, the discordance between mucosal and blood responses may highlight mechanisms contributing to recent vaccine failures.

Translocation (3;21;8)(q21;q22;q22) in a Patient with Acute Myeloid Leukemia: A Case Report and Review of Prognostic Indicators

We report a patient with acute myeloid leukemia (AML) and t(3;21;8)(q21;q22;q22). This translocation has not been previously described in de novo or relapsed AML. The patient is a 25-year-old woman who presented with WBC 6.2 x 10(9)/L, Hgb 10.2 g/dL, Hct 28.4%, and platelets 67 x 10(9)/L. A bone marrow biopsy revealed a 70% hematopoietic cellularity with 65% blasts. Immunophenotyping showed aberrant expression of lymphoid-associated marker CD19. Cytogenetic analysis on a 72-hour culture of bone marrow cells supplemented with conditioned media was evaluated by G-banding at about the 400-band level. The patients age, cytogenetics, WBC, and immunophenotype at diagnosis would seem to suggest a favorable prognosis, according to previous studies of prognostic indicators. She was treated with induction and consolidation chemotherapy, followed by myeloablative conditioning and autologous peripheral blood stem cell transplant (PBSCT). Despite multiple favorable prognostic factors, the patient relapsed 7 months after PBSCT. Translocation of chromosomes 8 and 21 is common in AML and is generally considered a good prognostic factor. We suspect that the effect of the 3q21 translocation in an otherwise favorable translocation of chromosomes 8 and 21 may be responsible for this patients early relapse.

Technetium-99m Sestamibi Scanning in Multiple Myeloma Stem Cell Transplantation

We report the use of technetium-99m sestamibi (MIBI) in a patient with multiple myeloma (MM) undergoing peripheral blood stem cell (PBSC) transplantation. MIBI is a radionuclide agent that is preferentially taken up by malignant tumors. Plain radiographs in a MM patient, taken prior to PBSC transplantation, showed a large right humeral lytic lesion that correlated with increased uptake of MIBI at the same location. MIBI uptake, demonstrating active MM bone disease, was also evident in areas which were normal on plain radiographs. Three months after PBSC transplant, the lytic lesion had healed by plain radiographs and repeat MIBI scan showed no uptake. MIBI scanning results have a positive correlation with plain radiographs, and more importantly, demonstrate active MM bone disease not yet detectable by plain radiographs. If MIBI proves more sensitive in the detection of MM bone disease than plain radiographs or bone scanning with traditional isotopes, it will have a significant role in the detection of early disease and in monitoring disease progression during and after therapy.