Variations in Screening Adenoma Detection Rate by Specialty of Physicians in a Predominately African American Population

Background: Screening colonoscopy aims to interrupt the adenoma-carcinoma sequence by removing all precancerous adenomatous polyps. Adenomatous polyp detection rate (ADR) can vary between endoscopists as well as between race, age, and risk of colorectal cancer (CRC). The purpose of this study was to compare ADR among academic gastroenterologists (A-GI), non-A-GI, and surgeons for endoscopies performed in the same endoscopic suite of a large medical center with a predominately African American (AA) population.

Methods: All screening colonoscopies performed in 2014 for patients aged 62-76 years were identified using the electronic medical records data. Patients with average risk and high risk of CRC defined as having a 'personal history of polyps' or 'family history of CRC', and history of ulcerative colitis and Fecal Occult Blood Test/Fecal Immunochemical Test (FOBT/FIT) positivity were included. Patients with incomplete colonoscopy (defined as failing to achieve cecal intubation or poor preparation) and unrecovered tissue biopsy were excluded. ADR was calculated for three groups of endoscopists: A-GIs, non-A-GIs, and surgeons.

Results: A total of 573 screening colonoscopies was analyzed. The endoscopists comprised five A-GIs, eight non-A-GIs, and six surgeons. The majority of patients were of AA decent (71%), female (54%) with an average age of 66 years. Patients classified as average risk comprised 79% of the population. Most of the colonoscopies were performed by A-GI (n=339), followed by non-A-GI (n=144), and surgeons (n=90). The ADR for A-GI was 50% as compared to 32% for non-A-GI (p<0.001) and 25% for surgeons (p<0.001). Also, A-GI were more likely to identify ≥3 adenomas during screening colonoscopies. Significant differences were observed (p<0.001) in the mean time of colonoscopy for A-GI (30 mins) non-A-G (14 mins), and surgeons (18 mins).

Conclusion: Significant variation in the ADR between endoscopists belonging to different specialties were observed. Although all appear to achieve acceptable ADR (ie at least 25 for men and 15 for women), academic gastroenterologists had better performance than non-academic GI and surgeons. This may be explained by a significantly longer average duration of procedures for the highest ADR group.

Performance characteristics of EUS-FNA biopsy for adrenal lesions: A meta-analysis

Background and Objective:

The role of EUS-FNA biopsy (EUS-FNAB) for detection of metastatic lesions (mets) to adrenals has not been evaluated systematically. Our aim is to systematically evaluate the performance characteristics of EUS-FNAB in detecting metastasis to the adrenal glands.

Materials and Methods:

We performed a systematic search on PubMed and OvidSP from January 1990 to July 2016 using various search terms for EUS and adrenal lesion. Only articles published in English literature were included in the study. Studies with fewer than 10 patients were excluded from the study. Publication bias was assessed using Begg-Mazumdar test and visual inspection of funnel plots.

Results:

Eight studies including 360 adrenal lesions that underwent EUS-FNAB were identified. Of these, 137 FNABs were conclusive for malignancy. Sensitivity of EUS-FNAB in detecting metastasis to the adrenals was 95% (95% confidence interval [CI]: 90%–98%) and specificity was 99% (95% CI: 96%–100%). Pooled positivity of EUS-FNAB in detecting lung cancer metastasis to the adrenals was 44% (95% CI: 31.5%–57.3%). No evidence of publication bias was noted.

Conclusion:

Our study demonstrates that EUS-FNAB is highly sensitive and specific in detecting metastasis to adrenals. It also shows that up to about half of the patients with lung cancer and adrenal lesions on imaging have metastasis, a finding with profound implications on lung cancer staging and treatment.

Immunotherapy for hepatitis B in the direct acting antiviral era: Reevaluating the thymosin α1 efficacy trials in the light of a combination therapy approach

Hepatitis B virus (HBV) causes both acute and chronic hepatitis and infects large numbers of individuals worldwide. Unfortunately, prediction of typical clinical outcome is problematic and there is considerable variability in the frequency, duration and severity of disease progression. The mainstay of HBV treatment is directed towards the suppression of HBV replication by nucleos(t)ide analogs (NUCs). The use of immunomodulators such as α-Interferon and thymosin α1 can, in select patients, results in elimination of both HBsAg and HBeAg. Given the observation that viral clearance is most effective in the presence of a strong immune response, this review summarizes data suggesting that the use of a combination of an immune modulator such as Tα1 with a highly effective NUC may result in a more successful therapeutic approach in patients with chronic hepatitis B (CHB). Results from small studies using combination Tα1 and NUCs are encouraging, and ongoing clinical trials combining entecavir with Tα1 are anticipated to provide important data assessing the use of a combination of Tα1 with a NUC to achieve resolution of CHB.

Decreasing racial disparity with the combination of ledipasvir-sofosbuvir for the treatment of chronic hepatitis C

African Americans (AA) in the US are twice as likely to be infected with hepatitis C virus (HCV) compared to the non-Hispanic-white US population (Cau). They are also more likely to be infected with HCV genotype 1, more likely to develop hepatocellular carcinoma, and, in addition, have a lower response rate to interferon-based therapies. With the increase in response rates reported for combinations of direct-acting antivirals, the possibility that racial disparity would be eliminated by agents that directly inhibit virus replication has become a reality. The objective of this review is to evaluate the literature from clinical studies and retrospective analysis with respect to the response of AA to the most prescribed antiviral combination sofosbuvir plus ledipasvir. While few studies have focused on AA patients, sufficient information is availed from the literature and studies in our predominately AA clinic population to confirm that ledipasvir–sofosbuvir has a similar effectiveness in AA as compared to Cau.

Immunostimulatory Activity of the Cytokine-Based Biologic, IRX-2, on Human Papillomavirus-Exposed Langerhans Cells

Langerhans cells (LCs) are the antigen-presenting cells of the epithelial layer and are responsible for initiating immune responses against skin and mucosa-invading viruses. Human papillomavirus (HPV)-mediated suppression of LC function is a crucial mechanism of HPV immune evasion, which can lead to persistent infection and development of several human cancers, including cervical, anal, and head and neck cancers. The cell-derived cytokine-based biologic, IRX-2, consists of multiple well-defined cytokines and is broadly active on various immune cell subsets. In this study, we investigated primary human LC activation after exposure to HPV16, followed by treatment with IRX-2 in vitro, and evaluated their subsequent ability to induce HPV16-specific T cells. In contrast to its activity on dendritic cells, HPV16 alone is not sufficient to induce phenotypic and functional activation of LCs. However, IRX-2 induces a significant upregulation of antigen presentation and costimulatory molecules, T helper 1 (Th1)-associated cytokine release, and chemokine-directed migration of LCs pre-exposed to HPV16. Furthermore, LCs treated with IRX-2 after HPV16 exposure induced CD8⁺ T-cell responses against specific HLA-A*0201-binding HPV16 T-cell epitopes. The present study suggests that IRX-2 is an attractive immunomodulator for assisting the immune response in eradication of HPV-infected cells, thereby potentially preventing HPV-induced cancers.

A short course of neoadjuvant IRX-2 induces changes in peripheral blood lymphocyte subsets of patients with head and neck squamous cell carcinoma

OBJECTIVE

IRX-2, a primary cell-derived biologic with pleotropic immune activity, was shown to induce increased lymphocyte infiltrations into the tumor of patients with head and neck squamous cell cancer (HNSCC) after 10 days of neoadjuvant therapy (Berinstein et al. 2011). In the same patients enrolled in the Phase II study, peripheral blood lymphocyte subsets were monitored pre- and post-IRX-2 therapy to evaluate changes induced by IRX-2.

METHODS

Absolute lymphocyte numbers were determined in whole blood using the TetraONE System. Lymphocytes were further separated on Ficoll-Hypaque gradients and evaluated by multiparameter flow cytometry. Lymphocyte numbers, including regulatory T cells (Treg) and naïve, memory and effector T cells, were compared in pre- and post-therapy specimens.

RESULTS

Total lymphocyte numbers remained unchanged after IRX-2 therapy. Significant changes occurred in numbers of circulating B cells and NKT cells, which decreased following IRX-2 therapy. The frequency of circulating Treg (CD4(+)CD25(high)) remained unaltered (e.g., 6.7 ± 0.6% vs. 7.5 ± 0.8%; means ± SEM) as was the CD8(+)/Treg ratio (6.6 before and 6.7 after IRX-2 therapy). The mean absolute number of CD3(+)CD45RA(+)CCR7(+) (naïve) T cells was decreased after IRX-2 therapy but numbers of total memory (i.e., central and peripheral) and terminally differentiated T cells were unchanged.

CONCLUSIONS

IRX-2-mediated reductions in B and NKT cell numbers in the blood suggest a redistribution of these cells to tissues. A decrease in naïve T cells implies their up-regulated differentiation to memory T cells. Unchanged Treg numbers after IRX-2 therapy indicate that IRX-2 does not expand this compartment, potentially benefiting anti-tumor immune responses.

Peptide Based Vaccine Approaches for Cancer-A Novel Approach Using a WT-1 Synthetic Long Peptide and the IRX-2 Immunomodulatory Regimen

Therapeutic cancer vaccines have the potential to generate a long lasting immune response that will destroy tumor cells with specificity and safety, in contrast to many other current cancer therapies. Clinical success to date has been limited by a number of factors including choice of immunogenic cancer rejection antigens, optimization of vaccine platforms and immune adjuvants to effectively polarize the immune response, and incorporation of strategies to reverse cancer mediated immune suppression by utilization of effective adjuvant/immune modulators. WT-1 (Wilms' tumor gene 1) is a cancer antigen that is required for tumorigenesis, expressed in a high percentage of tumor cells and rarely expressed in adult normal cells. Moreover spontaneous immunity to WT-1 is seen in cancer patients and can be augmented with various therapeutic vaccine approaches. IRX-2 is an immune modulator with demonstrated preclinical and clinical pleiotropic immune activities including enhancement of the immune response to potential tumor antigens. This paper presents the rationale and preclinical data for utilizing the WT-1 tumor antigen in a novel vaccine platform consisting of a synthetic long peptide containing multiple class I and class II epitopes in combination with the IRX-2 immunomodulatory regimen to overcome immuno-suppressive pathways and enhance the anti-tumor response.

Immunopharmacology of thymosin alpha1 and cytokine synergy

Thymosin alpha1 (Talpha1) is a 28 amino acid biologically active protein cleaved from positions 2-29 of a precursor protein, prothymosin alpha. Since its discovery, Talpha1 has been administered to animals and humans in a wide variety of settings and its pharmacologic effects are to enhance cellular immunity. Talpha1 administration is highly effective in settings where irradiation, chemotherapy, tumor burden, or immune senescence have caused a reduction of T cell number and/or function. Recent in vitro studies, including the one reported here, suggest that Talpha1 may act via pathways commonly used by various cytokines. This raises the possibility that Talpha1 and cytokines may have synergistic activity through potentiation of cytokine activity by Talpha1. Improved control of tumor growth when tumor-bearing mice were treated with Talpha1 and high doses of IL-2 has been previously reported. We extended those studies with the Lewis lung carcinoma mouse model using IRX-2, a natural well-defined biologic containing multiple cytokines, in combination with Talpha1 (IRX-3). Although IRX-2 was effective alone (using doses that contain significantly less IL-2 than in most typical studies), adding Talpha1 led to significant improvement in survival of the tumor-bearing mice. Based on these observations, the immunopharmacology of Talpha1 predicts an important clinical role for Talpha1 in the restoration of cellular immune activity when used in combination with cytokines. Patients who experience immune suppression due to the presence of tumor, irradiation, and/or chemotherapy or aging of the host would most benefit from this treatment combination.

Zadaxin (thymosin alpha1) for the treatment of viral hepatitis

Zadaxin (thymosin alpha1; Talpha1) is a synthetic 28 amino acid peptide with multiple biological activities primarily directed towards immune response enhancement. Since the immune system plays a critical role in the control and elimination of viral hepatitis infection, immune active agents such as Talpha1 are of potential therapeutic value. In clinical trials, Talpha1 has been shown to be effective in chronic hepatitis B, both asmonotherapy and in combination with interferon-alpha (IFN-alpha). In chronic hepatitis C it was effective in combination with IFN-alpha. Since Talpha1 has few side-effects and is effective in combination with IFN-alpha, future clinical trials should evaluate the potential of Talpha1 to enhance the activity of antivirals such as IFN-alpha, ribavirin and lamivudine as viral hepatitis therapy.

T cell targeted immune enhancement yields effective T cell adjuvants

Given the critical role of cell-mediated immunity (CMI) in defense against attack from pathogens that establish chronic infections, it has become abundantly clear that current vaccine methodology will not be sufficient to develop the appropriate immune response for protection and/or clearance of infection. By extension, this logic also applies to cancer vaccines where T cell immune-mediated destruction is a critical mechanism for control of the disease. This review describes our current thoughts on the events associated with immune activation and evaluates the various approaches to achieve successful immune activation with defined or targeted antigens as opposed to using inactivated or attenuated organisms. The advantages and disadvantages of the current adjuvants for antigens that focus on mimicking the infection events via the innate immune system or antigen uptake are described in the context of generation of T cell specific responses. A central theme of the discussions is the importance of cytokines in modulating the immune response towards T cell immunity, either by adjuvant modulation or use of natural cytokine mixtures targeted towards the site of immune activation. Also discussed is the possibility that thymomimetic agents such as thymosin alpha1, levamisole and methyl inosine monophosphate (MIMP) may be useful in enhancing the T cell mediated arm of the immune response.

African Americans with genotype 1 treated with interferon for chronic hepatitis C have a lower end of treatment response than Caucasians

African Americans as a group have a higher incidence of chronic hepatitis C (CHC) than Caucasians but are often under-represented in clinical trials used to define response rates to interferon therapy. The aim of this study was to compare African Americans with Caucasians with respect to end-of-treatment response to interferon. This retrospective study had 61 African Americans and 49 Caucasians with CHC. All patients were treated for at least 12 weeks with interferon-alpha2b (Intron A) thrice weekly. End-of-treatment response was defined as three consecutive nondetectable HCV RNA measurements at least 1 month apart. Sustained response was defined as a negative serum HCV RNA 6 months after end of treatment. Of the 110 patients, 19 achieved an end-of-treatment response (17%) but only four achieved a sustained response (4/110=4%). Of the patients achieving a sustained response, one was genotype 1 (male Caucasian), three were genotype 2/3 with four patients having no follow-up information. The end-of-treatment response was 7% for patients with genotype 1 and 71% for genotype non-1 (P < 0.005 for genotype non-1). The end-of-treatment response was significantly higher in Caucasians (14/49=31%) compared with African Americans (5/61=8%; P < 0.05). A lower response rate in African Americans with genotype 1 in contrast to Caucasians was the primary reason for the difference in end-of-treatment response (1/45=2% vs. 5/33=15%, P < 0.05). Hence, interferon treatment resulted in a poor sustained response rate in the group of patients representative of the urban populations with the highest prevalence of hepatitis C. A genotype other than type 1 was the strongest predictor of end-of-treatment response in patients treated but over 86% of patients in this urban clinic were genotype 1. Caucasians were more likely to respond than African Americans, especially in patients with genotype 1.

Effect of peptide-carrier coupling on peptide-specific immune responses

Synthetic peptides are covalently linked to immunogenic carrier proteins to enhance the anti-peptide immune response. To investigate whether the method of conjugation influences the immune response, we evaluated two distinctly different choices of linker for a peptide-carrier construct. HPG-30, a synthetic peptide derived from the p17 gag protein of human immunodeficiency virus 1, was covalently linked to keyhole limpet hemocyanin by either glutaraldehyde or a maleimide ester. Glutaraldehyde linkage enhanced the anti-peptide antibody and native protein response compared to maleimide. The maleimide-linked conjugate was more effective at inducing a peptide-specific cellular response. Thus, manipulation of the conjugation method can modify the magnitude and character of the immune response to a synthetic peptide vaccine.

Clonal growth inhibition as a bioassay for thymosin alpha1: inactivation of Talpha1 by trifluroacetic acid

Thymosin alpha1 (Talpha1) is an immune response modifying peptide isolated from thymus tissue. The synthetic peptide has been evaluated in clinical trials as an adjuvant to cancer chemotherapy, an enhancer of vaccine potency, and an anti-viral for both hepatitis B and C. Among its multiple in vitro activities is the inhibition of the clonal growth of hepatitis B transfected hepatoblastoma cells. This assay was used to define the relationship between bioactivity and immunoactivity of Talpha1. Talpha1 was treated with 50% trifluoroacetic acid (TFA) for 1 hr to inactivate the peptide. Talpha1 heated at 90 degrees C or at room temperature maintained its bioactivity but TFA completely eliminated the activity in the bioassay. The TFA inactivated Talpha1 had a retention time on reverse-phase chromatography identical to bioactive Talpha1 but reduced immunoreactivity. In addition to demonstrating the utility of clonal growth as a bioassay, these studies demonstrate that immunoreactivity rather than retention time on HPLC may be a better predictor of bioactivity of synthetic Talpha1.

TGFalpha is required for full expression of the transformed growth phenotype of NIH 3T3 cells overexpressing ornithine decarboxylase

Ornithine decarboxylase (ODC) overexpressed from a heterologous promoter drives the tumorigenic transformation of NIH 3T3 cells and provides a model to investigate the underlying molecular mechanisms. These transformed cells, designated NODC cells, exhibit elevated levels of epidermal growth factor receptor (EGFR) tyrosine kinase (Tyr-k) activity relative to control transfected cells and inhibition of EGFR Tyr-k activation suppresses the transformed growth phenotype of these cells. Thus, ODC-induced transformation of NIH 3T3 cells appears to be mediated, at least in part, by enhanced signaling through the EGFR pathway. Here we extend these studies by evaluating: (i) the effects on growth regulation of overexpressing ODC in EGFR-deficient NIH 3T3 cells; (ii) the potential role of TGFalpha in mediating the EGFR-dependent transformation of NIH 3T3 cells by ODC. Disruption of EGFR-TGFalpha interactions either by deleting EGFR, by treatment with anti-TGFalpha neutralizing antibody or by transfection with a TGFalpha antisense expression vector suppressed acquisition of the full transformed growth phenotype. Specifically, the loss of contact inhibition and the capacity for clonogenic growth appear more dependent on EGFR-TGFalpha interactions than anchorage-independent growth in ODC-overexpressing cells. ODC overexpression does not alter the amount, localization or secretion of TGFalpha. Thus, TGFalpha is not the ODC-responsive component of the EGFR signaling pathway but appears to be critically involved in development of the transformed phenotype of NODC cells.

Oral administration of interferon-alpha induces a transient decline in oral mucosal immunoglobulins and an increase in interleukin-5

Although administration of interferon-alpha (IFN-alpha) via the oral-mucosal route has shown efficacy in a variety of human and animal diseases, the mechanism of action of orally administered IFN is not clearly understood. To assess the possibility that IFN-alpha given via a lozenge alters the local mucosal immune system, immunoglobulins (Ig) and cytokines were measured in salivary secretions. Volunteers were given low doses of IFN-alpha and saliva was collected over a 24-h period. IgA and precursor IgM were measured by sandwich enzyme-linked immunosorbent assay (ELISA). Salivary concentrations of interleukin-5 (IL-5), the T helper cytokine primarily responsible for the switch from IgM to IgA, were also determined. After oral administration of IFN-alpha, there was an initial decline in IgM and IgA followed by a return to baseline levels by 8-24 h. This change in Ig concentration was associated with a gradual increase in IL-5, consistent with the return of Ig to baseline as a result of modulation by Ig-mediating cytokines.

Cytokine-mediated apoptosis and inhibition of virus production and anchorage independent growth of viral transfected hepatoblastoma cells

Cytokine-mediated apoptotic destruction of viral-infected cells, downregulation of virus production and inhibition of anchorage dependent (clonal) cell growth were evaluated using virus-transfected human hepatoblastoma (HepG2) cells. The cytokines evaluated were interferon alpha (IFN-alpha), tumour necrosis factor alpha (TNF-alpha) and thymosin alpha 1 (T alpha 1), all of which have previously been implicated in control of various viral infections. The viruses evaluated were Hepatitis B (HBV) and the transforming virus, SV-40. TNF-alpha-induced apoptosis in the HBV-transfected cell line and the control HepG2 cells but not the HepG2 cells transfected with SV-40 virus. IFN-alpha and T alpha 1 had no effect on apoptosis. TNF-alpha also prevented the clonal growth of the HBV-HepG2 and control HepG2 but enhanced the growth of the SV-40-transfected HepG2 cells. IFN-alpha inhibited the clonal growth of all three cell lines in contrast to T alpha 1 which inhibited the clonal growth of only the HBV-transfected cells. Although TNF-alpha, IFN-alpha, and T alpha 1 when given alone did not significantly inhibit HBV-DNA production in the culture supernatant from HBV-HepG2 cells, the combination of T alpha 1 and IFN-alpha resulted in a statistically significant inhibition of virus production. These studies demonstrate that HepG2 cells transfected with HBV and SV-40 are useful for defining the mechanisms of cytokine activity. The HBV-transfected cells are especially useful in defining possible in vivo differences in responses to cytokines with respect to HBV production, apoptosis and clonal cell growth. Multiple mechanisms through which different cytokines can influence HBV infection and hepatoblastoma growth were identified and the importance of defining effective combinations to improve therapy in vivo demonstrated.

Thymosin-alpha 1, but not interferon-alpha, specifically inhibits anchorage-independent growth of hepatitis B viral transfected HepG2 cells

BACKGROUND

Thymosin-alpha 1 is a biological response modifier that has been used clinically, alone and in combination with interferon-alpha for the treatment of chronic hepatitis B viral infection. Both immunomodulatory and immediate intracellular mechanisms have been postulated to explain the effect of these two agents on HBV-infected hepatocytes.

METHODS

In this study, hepatitis B transfected HepG2 hepatoblastoma cells (HepG2-Nu2), derived from 2.2.15 cells, were used as an in vitro model to determine the efficacy of thymosin-alpha 1 and interferon-alpha, individually and combined, as proliferation inhibitors of HBV-infected cells. For comparison, parental HepG2 cells and an SV40-transfected HepG2 cell line (HepG2P9T2) were also evaluated.

RESULTS

In a clonogenic soft agar assay, thymosin-alpha 1 inhibited the anchorage-independent growth of the HepG2-Nu2 cells by 40% compared with untreated controls, but did not inhibit parental HepG2 or HepG2P9T2 clonal growth. The response was dose dependent over concentrations spanning three log units. In comparison, 10000 units/ml of interferon-alpha inhibited parental HepG2, HepG2-N4Z and HepG2P9T2 by 33%, 41% and 87%, respectively. The combination of thymosin-alpha 1 and interferon-alpha consistently inhibited HepG2-Nu2 clonal growth more effectively than either treatment alone, reaching maximum inhibition levels of 51%.

CONCLUSIONS

Thymosin-alpha 1 specifically inhibits the tumorigenic growth of HBV-transfected HepG2 cells in contrast to the general inhibition displayed by interferon-alpha. This panel of cell lines may be an important resource for dissecting the mechanism by which thymosin, alone or in combination with other drugs, influences HBV-infected hepatocytes and/or HBV-associated carcinoma.

Thymus-derived peptides in the treatment of viral chronic hepatitis

The immune system plays a crucial role in the control and eventual clearance of hepatitis B virus (HBV) infection. Immune mechanisms are now believed to participate in the pathogenesis of the hepatitis C virus (HCV) and to account perhaps for the high frequency of progression from acute to chronic disease. Although IFN-alpha has been proven effective in the treatment of viral chronic hepatitis B and C, response rates are low, reactivation of disease is appreciable and side effects of treatment are frequent. Both antiviral and immune modulatory activity have been ascribed to IFN-alpha and are believed to account for its therapeutic effect. Immune-active peptides including those derived from the thymus have also been evaluated over the past 15 years for the treatment of viral chronic hepatitis. This review summarizes clinical studies and experimental observations which provide the rationale for the use of these agents in the treatment of chronic hepatitis associated with HBV and HCV. Primary attention is focused on thymosin-alpha (T alpha 1), a synthetic peptide, which has been evaluated in clinical trials. T alpha 1 has in vivo and in vitro immune-modulatory activity on lymphoid populations as well as the potential of more direct antiviral activity. Preliminary results of clinical trials utilizing combinations of T alpha 1 with various IFN preparations are also reviewed.

Thymosin alpha 1 does not promote growth or oncogenic transformation

Thymosin alpha 1 (T alpha 1) is an immune modulatory peptide which has been evaluated in a variety of clinical trials. Although no in vivo adverse effects, including enhancement of tumor growth, have been noted, in vitro studies suggesting a role for T alpha 1 in cell growth have been reported. The studies presented in this report evaluated both exogenously added T alpha 1 and endogenously expressed T alpha 1 as factors which could either promote growth of tumor cells or induce transformation. No effect of exogenous T alpha 1 on cell growth was found. NIH-3T3 cells transfected with cDNA for the precursor ProThymosin alpha (Pro T alpha) expressed elevated levels of authentic T alpha 1 but did not demonstrate either enhanced proliferation in liquid culture or transformation as defined by the loss of contact inhibition or anchorage independent growth in soft agar. Thus these studies argue against the hypothesis that T alpha 1 is either an intracellular or extracellular growth promoter.

Adjuvant properties of montanide CSA 720 with a recombinant HIV P17 gag protein and synthetic peptide antigens

The adjuvant properties of Montanide CSA 720 were assessed in a comparison with alum. BALB/c mice were immunized with recombinant HIV-1 gag protein p17 administered in either of the two adjuvants. The serum antibody response to p17 with Montanide CSA 720 appeared faster and reached a higher titre than with alum. The serum antibody response to p17 in Montanide CSA 720 was further characterized by a higher titre antibody directed against a 30 amino acid segment from the entire protein. The Montanide CSA 720 adjuvant was sufficiently strong to induce an antibody response against a weak synthetic peptide immunogen after two immunizations, while immunization with the peptide in alum generated no detectable serum antibody. The p17-specific proliferative response of splenocytes from animals immunized with recombinant protein in either adjuvant was similar.

HIV-1 p17 synthetic peptide vaccine HGP-30: induction of immune response in human subjects and preliminary evidence of protection against HIV challenge in SCID mice

An HIV-1 p17 subunit vaccine, HGP-30, was evaluated in 38 HIV-1 seronegative individuals in phase I clinical trials in U.K. and U.S.A. The vaccine preparation induced cytotoxic T-cell (CTL) (11/25) and lymphocyte proliferation responses to KLH (19/20) and HGP-30/p17 (24/29) as well as antibody responses to HGP-30 (29/38) and KLH (38/38). The CTL activity was observed in a higher number of vaccine recipients (9/18) in the lower dose groups (10 and 25 micrograms/kg) than the vaccine recipients (2/7) in the 50 and 100 micrograms/kg dose group. These observations suggest that the 10-25 micrograms/kg vaccine dose may preferentially induce TH1 cell responses. TH1 cell responses have been suggested as important in inducing protective cell mediated immunity. The CTL response has been shown to be CD8+. In a pilot study in SCID mice, HIV-1 virus challenge studies in mice reconstituted with cells from an HGP-30 immunized individual showed protection against virus challenge as compared to SCID mice reconstituted with cells from a non-immunized subject. These studies suggest that HGP-30 is capable of inducing protective cellular immunity.

Thymosin beta 4 synergizes with human granulocyte-macrophage colony-stimulating factor in maintaining bone marrow proliferation

Recent evidence supports a role for thymosin beta 4 (T beta 4) in the inhibition of murine hematopoietic stem cell proliferation. This supposition results from studies in which the N-terminal tetrapeptide derived from native T beta 4 was administered to mice and appeared to prevent CFU-S recruitment into DNA synthesis. The importance of this observation was the concomitant ability of the tetrapeptide to prevent cytosine arabinoside (ara-C) toxicity in mice given LD50 doses of this drug. In the present study, we have extended these observations by demonstrating that whole synthetic T beta 4 is more effective than the N-terminal tetrapeptide in protecting mice from the toxicity of ara-C. This observation supports the hypothesis that T beta 4 is the biologically important parent molecule for this activity. To determine if inhibition of cell cycle progression also occurs in committed human bone marrow progenitors treated with T beta 4, we have investigated the effects of synthetic T beta 4 on proliferating and unstimulated enriched human bone marrow. In short-term liquid cultures studied sequentially over 1-7 days, T beta 4 failed to inhibit cell proliferation, but maintained the proliferative effect of granulocyte-macrophage colony stimulating factor (GM-CSF) on days following maximum stimulation (days 5-7). No effect was noted before the fifth day in culture, nor did T beta 4 exert any demonstrable effect in the absence of added GM-CSF. Any observable effect of T beta 4 required that it be present in the cultures on or before day 3 of GM-CSF stimulation. These results suggest that an additional effect of T beta 4 is the stimulation of a subpopulation of committed human bone marrow precursor cells to become more sensitive to the growth-promoting activity of GM-CSF, thereby enhancing myelopoiesis. It is of interest that the N-terminal peptide of T beta 4 is a shared sequence with tumor necrosis factor alpha, which is also known to have a similar stimulatory capacity. We, therefore, postulate that the growth enhancement noted in short-term cultures is mediated by the region containing these shared sequences.

Serum cross-reactive thymosin alpha 1 levels in rats during induction of mammary carcinoma with 7,12-dimethylbenz[a]anthracene: short- and long-term effects

The levels of serum cross-reactive thymosin alpha 1 (CRT alpha 1) were measured at various time intervals during the course of development of mammary tumors in female Sprague-Dawley rats intubated with 7,12-dimethylbenz[a]-anthracene (DMBA; 10 mg/rat). Matched control rats were also tested simultaneously. An increase in CRT alpha 1 in DMBA-treated animals was observed within 2 h of DMBA treatment. Thereafter the levels of CRT alpha 1 in the serum of the DMBA-treated rats remained elevated for another 3 weeks prior to declining to control levels. Levels remained stationary until an increase in serum CRT alpha 1 was observed at 9-11 weeks post-DMBA treatment. This correlated with the time when mammary tumors were either palpable or observed. Levels of CRT alpha 1 fell at 13 weeks but remained slightly elevated until sacrifice due to tumor burden at 18 weeks.

Identification of immunoreactive forms of thymosin alpha 1 in serum and supernatants by combining HPLC and RIA

Thymosin alpha 1 (T alpha 1) is a biologically active peptide, originally isolated from the thymus and currently undergoing clinical trials as an immunomodulator in cancer patients, in individuals with chronic active hepatitis, and as an immunoenhancer of vaccines in immunocompromised individuals. Absorption of rabbit antibody to thymosin alpha 1 with a synthetic C-14 fragment of T alpha 1 results in an antiserum with increased affinity for the amino terminal region of T alpha 1 and the precursor protein prothymosin alpha (ProT alpha). Using HPLC methodologies, the predominant form of immunoreactivity in serum and thymus was T alpha 1 not the precursor. Using this assay we detected a decline in mouse serum T alpha 1 following irradiation but not thymectomy, an observation consistent with the existence of an important radiation sensitive lymphoid source of serum T alpha 1. The secretion of authentic T alpha 1 but not the precursor into culture medium by thymic epithelial cells as well as in mitogen-stimulated peripheral blood lymphocytes was also demonstrated by HPLC/RIA. HPLC analysis by molecular weight sizing columns demonstrated that unlike thymic epithelial cells or peripheral blood lymphocytes, the immunoreactive T alpha 1 (IRT alpha 1) form in the supernatants from tumor cells such as MCF-7 breast carcinoma was of a lower molecular weight than authentic T alpha 1. These studies suggest that the authentic form of T alpha 1 is the major immunoreactive form in normal serum and that it is secreted by the medullary thymic epithelial cells as well as by peripheral blood lymphocytes. An additional immunoreactive form, secreted by tumor cells has also been identified and is the subject of future studies.

A phase I study of HGP-30, a 30 amino acid subunit of the human immunodeficiency virus (HIV) p17 synthetic peptide analogue sub-unit vaccine in seronegative subjects

HGP-30-KLH vaccine in alum at doses of 10, 25, 50, and 100 micrograms/kg administered intramuscularly at weeks 0, 4, and 10 appear well-tolerated clinically. Local pain at the injection site, appears to be the main clinical toxicity. Laboratory parameters are not affected by administration of the vaccine candidate except for perhaps mild urinalysis abnormalities at the highest dose. This vaccine candidate has no apparent immunotoxicity and does not appear to affect lymphocyte populations or T-cell functional studies. Low levels and transient antibodies develop in a minority of subjects early after immunization with the vaccine candidate. These responses were observed in the lowest dose range. Higher doses, and longer follow-up will be needed to confirm this observation. T-cell proliferative responses to KLH and KLH-HGP-30 are consistent and may not be dose dependent, but the proliferative responses are variable and more data need to be accumulated. Preliminary, there appears to be an HGP-30-induced CTL response of HGP-30-coated EBV-transformed autologous B cell lines. This study was approved under an IND for the California Department of Health Services' Food and Drug Branch. They have provided excellent support and regulatory guidelines for this project. Future work will extend and confirm these initial observations.

Specific antibody responses to synthetic peptides of HIV-1 p17 correlate with different stages of HIV-1 infection

Antibodies were determined against five synthetic peptides (epitopes) of HIV-1 p17 in the sera of an immunologically and clinically well-characterized cohort (N = 292) of HIV-1 seronegative and HIV-1 seropositive high-risk homosexual men, HIV-1 seropositive i.v. drug abusers (IVDA), and AIDS patients. The synthetic peptides, representing the entire HIV-1 p17 protein sequence were: HGP-33 (aa 1-33), HGP-19 (aa 34-52), HGP-35 (aa 51-85), HGP-30 (aa 85-114), and HGP-17 ala (aa 114-131). The presence of one or more peptide-specific antibodies in the sera of all of the HIV-1 p17-positive subjects indicated that all five peptides contain B-cell epitopes. No antibodies were found in the sera of heterosexual controls, HIV-1 seronegative high-risk men, or asymptomatic HIV-1 seropositive but p17 antibody-negative study subjects. Significant differences in antibody recognition profiles to the peptide epitopes were found among the various study groups. A significantly higher proportion of HIV-1 seropositive IVDA had antibodies specific to HGP-17 ala (aa 114-131), HGP-35 (aa 51-85), and HGP-33 (aa 1-33) compared to the HIV-1 p17-positive asymptomatic homosexuals. The epitope-specific antibody responses reflected the clinical status of the HIV-1-infected study subjects, and declined to nondetectable levels as the patient progressed to ARC/AIDS. This decline preceded by several months the reduction in the antibody titer against the intact HIV-1 p17 and p24 proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell-mediated immunity against HGP-30, a group-specific peptide of HIV p17 in individuals infected with the AIDS virus

HGP-30, the synthetic peptide analogue and active component in an HIV-1 (human immunodeficiency virus, type 1) p 17 core-based experimental vaccine, has previously been shown to induce cytotoxic and helper T-lymphocyte responses. In order to further define the T-helper cell responses which are known to play a role in enhancing the immunological response to foreign antigens, we studied the response of individuals infected with HIV to HGP-30 at various stages of disease progression. We have investigated the proliferative cellular response of peripheral blood mononuclear cells (PBMCs) derived from individuals infected with HIV-1 to HGP-30. We have found a PBMC proliferative response to HGP-30 in 40% of the healthy seroconverted patients, in 35% of the CDC stage III patients and in 18% of the CDC stage IV patients. There was no correlation between the proliferative response to HGP-30 and other antigens such as HIV-like proteins or tetanus toxoid not to CD4 cell count. HLA-DR typing revealed the possible presentation of HGP-30 by several different class II molecules. Since these class II molecules occur frequently in the general population, HGP-30 appears to contain broadly reactive epitopes and thus is not restricted as are many peptide vaccines. Due to its broad reactivity and extreme conservation in many HIV-1 strains. HGP-30 is one of the promising candidates for inclusion as a subunit vaccine against HIV-1.

Effects of PCB (Aroclor 1254) on non-specific immune parameters in rhesus (Macaca mulatta) monkeys

The effects of low level, chronic polychlorinated biphenyl--Aroclor 1254--(PCB) exposure were investigated on non-specific immune parameters in female rhesus (Macaca mulatta) monkeys. Five groups of monkeys were orally administered with PCB at concentrations of 0, 5, 20, 40 or 80 micrograms/kg bw/day. Immunotoxicity testing was initiated after 55 months of exposure. The serum hemolytic complement activity in all PCB treated groups was significantly higher (P less than 0.05) than that in the control group. A statistically significant dose-related increase in natural killer cell activity was evident at the 75:1 effector to target cell ratio. Similarly, a statistically significant dose-related increase was noted for thymosin alpha-1 levels but not for thymosin beta-4 levels. Statistically significant increased interferon levels were noted in the 20 and 80 micrograms/kg groups compared with the control group while the levels in the 40 micrograms/kg group were decreased significantly compared with the control group. The production of tumor necrosis factor by monocytes in the PCB treated groups was not different to that in the control group. The results indicated that long term exposure to PCB modulate several non-specific immune parameters.

Low thymosin alpha-1 concentrations in patients chronically infected with the hepatitis B virus

Serum concentrations of thymosin alpha-1 (TA-1), an immunoregulatory peptide, were assayed in patients with chronic hepatitis B infection and volunteer blood donor controls. Coded samples were tested using a radioimmunoassay. The TA-1 concentrations in HBsAg-positive patients averaged 1555 pg/ml, whereas in the control group, the mean TA-1 in serum was 2159 pg/ml (P less than 0.001). Similar results were found for age- and sex-matched pairs. The TA-1 concentration was not associated with HBe antigen/antibody status or with values of liver-associated enzymes. Analysis of T-cell subsets in nine HBsAg carriers revealed significantly decreased CD4 (helper)-cells, both in absolute numbers and as the percentage of total lymphocytes present. These data suggest that individuals with chronic hepatitis B infection have a relative deficiency of the immunomodulatory peptide TA-1, which may contribute to the characteristics of the resultant T-cell population.

Preclinical and clinical studies on immunogenicity and safety of the HIV-1 p17-based synthetic peptide AIDS vaccine--HGP-30-KLH

Immunization with a synthetic HIV-1 p17 peptide analog (HGP-30; aa 85-115 of HIV p17), coupled to a carrier protein (KLH, keyhole limpet hemocyanin) given with alum as the adjuvant induces antibodies which cross-react with both HGP-30 and HIV p17 and clones of cytotoxic and helper T-cells which recognize HGP-30 and HIV p17. Proliferation of lymphocytes in response to HGP-30 has been observed in mice, in HIV-infected individuals and in healthy HIV-seronegative volunteers vaccinated with the p17-based synthetic peptide construct. Cytotoxic T-cell responses against EBV transformed, recombinant p17 pulsed targets were observed using antigen-expanded PBLs from HGP-30-KLH immunized individuals. These results are consistent with predictions that the HGP-30 domain of HIV p17 contains both T- and B-cell epitopes that are recognized by animals and humans. In preclinical toxicology studies in animals and in initial clinical trials in humans the synthetic peptide construct (HGP-30-KLH/alum) has been shown to be safe. This paper summarizes the preclinical immunogenicity and safety data for HGP-30-KLH and presents the initial results from the first Phase 1 clinical trial.

HGP-30, a synthetic analogue of human immunodeficiency virus (HIV) p17, is a target for cytotoxic lymphocytes in HIV-infected individuals

Evaluation of the immune response of individuals exposed to human immunodeficiency virus (HIV) is an important component of any plan designed to lead toward the development of an AIDS vaccine. Since the levels of antibodies to HIV p17 and the synthetic p17 peptide HGP-30 correlate with stages of progression to AIDS, studies were initiated to determine whether cytotoxic lymphocytes directed toward target cells pulsed with HGP-30 and radioactive chromium were present in seropositive individuals. The significance of such cells in controlling HIV viral infection has recently been enhanced by reports that HIV p17 is on the surface of infected cells and that an inactivated virus vaccine depleted of viral envelope appears to be effective in controlling expression. The selection of HGP-30 as the p17 peptide to be evaluated in early studies is based on the presence of both T-cell and B-cell epitopes as predicted by computer modeling and mouse studies and the demonstration of in vitro neutralization activity by antibodies to the epitope. By using B-lymphoblastoid cells pulsed with HGP-30 and radioactive chromium as autologous targets and mixed leukocyte culture-expanded peripheral blood lymphocytes as effectors, CD8+ cytotoxic T lymphocytes against HGP-30-coated targets were identified in seropositive individuals. In this report we demonstrate that a synthetic p17 epitope can be a target for major histocompatibility complex-restricted cytotoxic T lymphocytes in HIV-infected individuals.

Cellular levels of thymosin immunoreactive peptides are linked to proliferative events: evidence for a nuclear site of action

Thymosin alpha 1 (T alpha 1), the N-terminal 28-amino acid fragment of prothymosin alpha (ProT alpha), and ProT alpha, although originally isolated from whole thymus extracts, are also present in nonthymic cells and tissues. We used an ELISA with an antibody raised against T alpha 1 to investigate the relationship between intracellular levels of thymosin immunoreactive peptide(s) (TIP) and cell proliferation in a rat small intestinal IEC-6 cell line. Increasing TIP levels were observed during cell proliferation, which decreased when proliferation was halted by cellular contact inhibition. Serum feeding of cells previously rendered quiescent by serum starvation resulted in a significant increase in TIP within 1 hr. Conversely, serum starvation decreased TIP levels within 1 hr. Peak TIP levels appeared after 3 hr of serum incubation, while maximum [3H]thymidine incorporation was noted after 9 hr, suggesting maximum TIP concentrations in the G1 phase of the proliferative cycle. Immunoelectron microscopy demonstrated an association of TIP with condensed nuclear chromatin. These results support a relation of intracellular TIP levels to IEC-6 cell proliferation and also a nuclear site of action. HPLC analysis of cellular homogenates from proliferating IEC-6 cells revealed a peak of immune reactivity that elutes in the position of T alpha 1.

Acute and chronic effects of diethylstilbestrol on serum levels of alpha melanocyte stimulating hormone and prolactin in the hamster

Continuous exposure to diethylstilbestrol (DES) induces renal tumors in male hamsters. The tumor formation is preceded by an increase in pituitary weight and elevation of the pituitary hormones-alpha melanocyte stimulating hormone (aMSH) and prolactin (Pr1). A decline in Pr1 (to normal levels) but not aMSH then accompanies the development of tumors and the enlargement of the intermediate lobe of the pituitary. Hypophysectomy, castration and thymectomy reduced serum levels of aMSH. DES administered for one week increased the serum levels of both hormones in normal and castrated animals, but not in hypophysectomized hamsters.

Changes in circulating levels of neuroendocrine and thymic hormones during aging in rats: a correlation study

It is well established that during early life the thymus gland and the neuroendocrine system influence each other's maturation. Furthermore, there is a growing body of evidence indicating that the immune and neuroendocrine systems also function as a bidirectional network during adult life. In order to assess possible changes in the thymic-neuroendocrine network during aging, we undertook to measure and correlate the circulating levels of several neuroendocrine and thymic hormones in young (3 month) and old (26 month) male Sprague-Dawley rats. Sequential plasma samples were obtained from chronically cannulated, nonstressed animals every 30 min for 5 h. Two days later rats were killed between 11:30 a.m. and 1:30 p.m. and trunk serum was obtained. All hormones were measured by radioimmunoassay. Growth hormone (GH), prolactin (PRL), thyrotropin (TSH) and corticosterone were measured in plasma, whereas thyroxine (T4), triiodothyronine (T3), thymosin alpha 1 (T alpha 1) and thymosin beta 4 (T beta 4) were determined in trunk serum. The circulating levels of T3, PRL, corticosterone and T beta 4 did not show significant differences between young and old rats, whereas GH, T4, T alpha 1, and thymus weight showed a significant age-related reduction. The anterior pituitary (AP) weight and plasma TSH were significantly higher in old than in young rats. Three pairs of parameters showed highly significant levels of linear correlation: AP weight vs. T alpha 1; thymus weight vs. T4 and T alpha 1 vs. T4 (p less than 0.01, p less than 0.001 and p less than 0.001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Immune response and epitope mapping of a candidate HIV-1 p17 vaccine HGP30

A thirty amino acid synthetic peptide (HGP30) representing the conserved region of HIV-1 p17 induced high titer antibodies to the native p17 in rabbits. This immune sera neutralized HIV-1 replication in cell culture and one of the high titer antisera also inhibited CD4-dependent cell fusion. Pepscan analysis with overlapping nonapeptides derived from the sequence of HIV-1 p17 identified the sequence (KE) ALDKIEE (EQ) as the major antibody binding site. Sera of 9% of AIDS patients (7/76) and 18% of HIV-1 seropositive healthy homosexuals (40/223) were positive for HGP30 antibodies. Decline in HIV-1 p17 antibodies has been shown to be related to disease progression in both children and adults, suggesting that HIV-1 p17 antibodies may be protective. Hence, a synthetic HIV-1 p17 peptide, representing the immunodominant epitope, could be useful as a candidate vaccine for immunization of HIV-1 seronegative or seropositive healthy homosexuals.

Diminished thymosin alpha-1 levels in persons exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

There is evidence from animal studies that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) impairs immune responses, with the thymus being a principal target organ. The purpose of this study was to evaluate thymic function, through measurement of thymic hormone levels, in persons exposed to TCDD. We examined thymosin alpha-1 (Thya-1) levels in sera from a group of 94 persons who were presumed to be exposed to TCDD from living, working, or recreating in a contaminated residential area. We compared these results, along with results from in vitro and in vivo tests of immune function, with those from a group of 105 unexposed persons who were similar with regard to age, sex, and race. The exposed group had a significantly lower mean Thya-1 serum level (977.3 +/- 304.1 pg/ml vs. 1148.7 +/- 482.1 pg/ml, p less than .01 by t-test). We also found a statistically significant trend of decreasing Thya-1 levels with increasing number of years of residence in the TCDD-contaminated area. However, Thya-1 levels were not associated with other measures of immune function in the TCDD-exposed group. Thus, while the principal findings suggest that long-term TCDD exposure may be associated with diminished secretion of Thya-1, the lack of an association with an increased prevalence of clinically diagnosed immune suppression in these TCDD-exposed persons makes the biologic significance of the findings unclear. Further studies are needed to more fully evaluate possible long-term TCDD-induced effects on the thymus and human immune function.

Thymosin alpha 1 in milk specimens from Guatemalan women

Thymosin alpha 1 was determined in milk samples obtained from 67 Guatemalan women 5 days, and 1-3 and 6-18 months postpartum. All the specimens collected 5 days after delivery contained measurable levels (583 +/- 304 pg/ml) of thymosin alpha 1 but only 33% of those obtained 1-3 months postpartum and none collected thereafter did. Since thymosin alpha 1 has been shown to increase T-cell mediated immunity, and to enhance host resistance to infection, it may play an important role in the maturation of mucosal immunity and host resistance in general in the neonate. This study is the first to document the presence of a thymic hormone in early postpartum milk.

Influences of aging and dietary restriction on serum thymosin alpha 1 levels in mice

Influences of age (3 wk, 2, 7, 19, or 26 mo), long-term dietary restriction (DR) started at 3 wk of age, and acute fasting state on serum thymosin alpha 1 (T alpha 1) levels were measured by radioimmunoassay in female mice from a long-lived strain. The average T alpha 1 level was highest (approximately 60 ng/ml) at 3 wk and fell sharply such that 2 mo old mice fed either normal (N, approximately 80% of ad libitum intake) or restricted (R, approximately 50% of ad libitum intake) diets averaged approximately 20 ng/ml. Any age-related declines after 2 mo of age were mild and statistically significant only for R mice bled 2-4 h (but not 24-48 h) post-feeding. T alpha 1 levels were lower in group R than in group N mice in one experiment at 19 mo of age but not in another at 26 mo. The decline with age in serum T alpha 1 levels is mainly a very early life event for mice of this hybrid strain and appears uninfluenced by DR. T alpha 1 levels are variably reduced by DR later in life.

Enzyme immunoassay measurement of thymosin beta 4 in human serum

An enzyme immunoassay (EIA) for measurement of human serum thymosin beta 4 is described. Antiserum to synthetic thymosin beta 4, raised in rabbits, is incubated with a standard or serum. The unbound antibody in liquid-phase then binds with solid-phase thymosin beta 4. The EIA is both sensitive and accurate and is capable of detecting as little as 2.5 ng/ml thymosin beta 4 in serum. No cross-reactivity was observed with common serum proteins or other putative thymic hormones. High-performance liquid chromatography of serum samples reveals a single thymosin beta 4 peak that corresponds to the authentic thymosin beta 4 peak in the standard. Human serum levels range from 3 to 82 ng/ml in 142 healthy adult human volunteers. Newborn cord serum levels of thymosin beta 4 are lower than in adults.

Improved ELISA to measure thymosin alpha 1: comparison of whole and absorbed antisera

An improved microELISA to measure thymosin alpha 1 (T alpha 1) is described which uses a rabbit antibody against T alpha 1 that has been absorbed with a synthetic C-14 fragment of T alpha 1. This assay is compared to the previous assay which used the whole antisera. The antibodies to T alpha 1 are preincubated with the standard or human sera overnight at 4 degrees C, then incubated for an additional 24 h in microtiter plates coated with T alpha 1. Using the whole antiserum, the average T alpha 1 level was 2480 +/- 1110 (mean +/- S.D.) pg/ml by ELISA and 2360 +/- 870 pg/ml by radioimmunoassay (RIA) in eight different samples of human cord sera. Using the N-specific absorbed antiserum the mean T alpha 1 level was 11,800 +/- 4800 pg/ml by ELISA and 10,600 +/- 5200 pg/ml by RIA. Recoveries of exogenously added T alpha 1 are complete (109 +/- 25% for whole and 108 +/- 15% for absorbed antisera). The absorbed antiserum has an increased affinity for the amino acid terminal region of T alpha 1 and the T alpha 1 values by use of absorbed antisera are significantly higher (3-5 x) than those measured using the whole antisera. Thus, the absorbed antisera produces an ELISA which is more sensitive and specific for serum thymosin alpha 1.

Thymosin alpha 1 levels in human seminal plasma and follicular fluid: implication in germ cell function

High levels of thymosin alpha 1 (T alpha 1) were detected in human seminal plasma and follicular fluid. In the seminal plasma of 19 males studies, T alpha 1 levels varied from 614 to 2,604 pg/mL (mean +/- SD, 1,682.4 +/- 453.9 pg/mL). There was a correlation between the T alpha 1 levels and the total number of sperm in the ejaculate (r = .18) and seminal volume (r = .26). The infertile males, who had low levels of T alpha 1 also demonstrated fewer sperm, reduced motility, and lower semen volume. In follicular fluid collected from 24 follicles of 10 infertile females, T alpha 1 levels varied from 1,019 to 6,384 pg/mL (mean +/- SD, 3,572.8 +/- 1,599.7 pg/mL), which were higher when compared with the corresponding serum levels (mean +/- SD, 1,666.9 +/- 1,378.9 pg/mL). T alpha 1 levels present in follicular fluids which had "immature" oocytes were lower when compared with follicular fluids which had "intermediate" or "mature" oocytes. The immunoreactive T alpha 1 present in seminal plasma of males and in the follicular fluids of females may be involved in some aspect of germ cell maturation and function. The measurement of T alpha 1 levels may be useful in the diagnosis and treatment of male and female infertility, and also as a novel marker for the assessment of maturity of oocytes required for in vitro fertilization-embryo transfer.

Human immunodeficiency virus contains an epitope immunoreactive with thymosin alpha 1 and the 30-amino acid synthetic p17 group-specific antigen peptide HGP-30

We have reported that an antiserum prepared against thymosin alpha 1 [which shares a region of homology with the p17 protein of the acquired immunodeficiency syndrome (AIDS)-associated human immunodeficiency virus] effectively neutralized the AIDS virus and prevented its replication in H9 cells. Using HPLC and immunoblot analysis, we have identified from a clone B, type III human T-lymphotropic virus (HTLV-IIIB) extract a protein with a molecular weight of 17,000 that is immunoreactive with thymosin alpha 1. In contrast, no immunoreactivity was found in retroviral extracts from a number of nonhuman species including feline, bovine, simian, gibbon, and murine retroviruses. Heterologous antiserum prepared against a 30-amino acid synthetic peptide analogue (HGP-30) does not cross-react with thymosin alpha 1 but does react specifically with the p17 protein of the AIDS virus in a manner identical to that seen with an HTLV-IIIB p17-specific monoclonal antibody. The demonstration that this synthetic analogue is immunogenic and that antibodies to HGP-30 cross-react not only with the synthetic peptide but also with the HTLV-IIIB p17 viral protein provides an additional, and potentially more specific, candidate for development of a synthetic peptide vaccine for AIDS. In addition, the p17 synthetic peptide (HGP-30) may prove to be useful in a diagnostic assay for the detection of AIDS virus infection in seronegative individuals.

Localization of thymosin alpha 1 production to thymus medullary epithelial cells by use of monoclonal antibodies

The thymus is an endocrine organ which modulates T-cell immunity through the production of protein like peptides such as the thymosins. Thymosin alpha 1 was the first biologically active peptide isolated and sequenced from the partially purified thymic preparation, thymosin fraction 5, and has been extensively studied. Using synthetic Thymosin alpha 1, a heterologous rabbit antiserum has been raised and a radioimmunoassay has been developed. Although thymosin alpha 1 antibodies have been used in several histological studies, their use is limited by potential nonspecific cross-reactivities, unpredictable heterogenicity, variable affinities, and a limited unstandardized supply. In the studies, reported here, eight anti-thymosin alpha 1 monoclonal antibodies (MAbs) were produced by somatic cell fusion between spleen cells from immunized BALB/c mice and P3x64 Ag8.653 myeloma cells. The MAbs were screened for anti-thymosin alpha 1 specificity in a solid phase ELISA and a liquid phase RIA. Only those clones which secreted specific antibody as detected by both procedures were characterized for their heavy chain class and epitope specificity. The anti-thymosin alpha 1 monoclonal antibodies were then used for indirect immune fluorescence studies of perfused rat thymus. Thymosin alpha 1 containing cells were found primarily in the thymic medulla, confirming previous studies using the heterologous antisera. These studies demonstrated the specificity of the anti-thymosin alpha 1 monoclonal antibodies for immunochemical studies of intra- and extra-thymic localization of thymosin alpha 1. They also provide an important reagent for biological studies of the role of thymosin alpha 1, in vitro and in vivo.

Thymosins and anti-thymosins: properties and clinical applications

For years, scientists have searched for ways to trigger the body's own defenses against cancer and other diseases associated with abnormal immunity. This search has led to the discovery of a number of important new biological and chemical substances that augment, direct or restore many of the normal defenses of the body. These substances are in essence the natural drugs of the body that endow us with immunity and resistance to disease. Now called biological response modifiers (BRMs), most of these 'new medicines', such as thymosins, lymphokines, and interferons, occur naturally in the body, while others, synthetic immunomodulators and thymomimetic agents (drugs that mimic thymic function) have been created in the laboratory. Previously, therapeutic drug development in this area relied upon chemical synthesis or introduction of bacterial adjuvants, or modified viral compounds and substances, which were foreign to the body. Therefore, they did not and do not rely upon or use the body's natural immune and biological response systems for protection against disease, function and response to the environment. Although scientists have known about BRMs for years, isolating and purifying them so that they could be used to treat diseases has been extremely difficult. Many of these substances, such as the lymphokines, occur in the body in minute amounts and normally do not circulate in the blood. The development of new technologies for isolation and large scale synthesis, e.g. solid phase peptide synthesis, high-pressure liquid chromatography microsequencing and genetic engineering, has now permitted scientists to isolate, purify, and synthesize BRMs in sufficiently large quantities to allow human clinical trials. In this paper we will focus on the potential clinical applications of the thymosins and anti-thymosins.

Circulating thymulin and thymosin-alpha 1 activity in pediatric acquired immune deficiency syndrome: in vivo and in vitro studies

Twenty-five children with acquired immune deficiency syndrome (AIDS) or AIDS-related complex had a characteristic pattern of T cell deficiency. Abnormally low plasma thymulin levels preceded the development of peripheral blood T cell abnormalities. In contrast to patients with congenital T cell deficiencies, our patients had elevated serum levels of thymosin-alpha 1. Treatment with thymosin fraction 5 in three children with AIDS resulted in only transient clinical and immunologic improvement.