Effect of thymosin in vitro on T cell levels during radiation therapy: correlations with radiation portal and initial T cell levels

Overview of immunology of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy and is a major cause of cancer morbidity and mortality worldwide. Every year, approximately 500,000 new cases of oral and pharyngeal cancers are diagnosed worldwide, and a majority of these cases are seen in developing countries. OSCC arises as a result of multiple molecular events that develop from the combined influences of an individual's genetic predisposition and exposure to environmental carcinogens. Here, we discuss the course of immunological development involving OSCC. We have reviewed a literature available in Medline and Google databases. We draw attention to possible shortcomings and issues requiring clarification. Emphasis is given to precise immunology involving the OSCC. In this article, we try to approach the immunology of OSCC through a practical approach consideration of common difficulties and dilemmas faced by the oral pathologist, and where possible, we offer guidance and practical tips. The article concludes with a brief consideration of the prognostic value of immunology involving the OSCC.

Cellular immune defect caused by postsurgical radiation therapy in patients with head and neck cancer

The effects of locoregional postoperative radiation therapy (60 Gy on average) on cellular immunity were investigated in 11 patients with squamocellular carcinomas of the oral cavity, pharynx, or larynx. During radiation treatment, the total lymphocyte counts, CD8+ T-lymphocyte count, and especially CD4+ T-lymphocyte count decreased significantly. The mean CD4+ T-lymphocyte counts dropped from an average of 739/microl to 183/microl (p <0.001), and the CD4+/CD8+ quotient also decreased significantly. Not only the lymphocyte counts but also the in vitro lymphocyte stimulation responses to several mitogens decreased, with reductions averaging 10% to 50% of normal responses by the end of radiation therapy. Within 3 to 4 weeks after radiation therapy, the CD4+ T-lymphocyte counts and the in vitro lymphocyte stimulation responses showed a tendency toward normalization. This study shows that postoperative locoregional radiation therapy in patients with head and neck cancer induces a severe generalized impairment of cellular immunity.

The effect of radiation therapy on immune function in patients with squamous cell lung carcinoma

The immune response is impaired in patients with malignancy, and radiation therapy (RT) can exacerbate the cancer induced-attenuation of immune response. In order to search for the fine mechanisms behind the RT-induced attenuation of cell-mediated immune response, we measured the number of lymphocytes in peripheral blood, its subsets, and lymphoblast transformation induced by phytohemagglutinin (PHA), purified protein derivatives (PPD), mitogenic monoclonal antibody anti-CD3, and mitogenic combination of anti-CD2 antibodies 9-1 and 9.6 before and after RT in 19 patients with squamous cell lung cancer. Radiation therapy significantly decreased the total numbers of lymphocytes, CD-3, CD-4, and CD8-positive lymphocytes in peripheral blood. However, RT did not change the percentages of lymphocytes and its subsets. Radiation therapy increased the percentage of interleukin 2 (IL-2) receptor-positive lymphocytes, and RT significantly decreased in vitro lymphoblast transformation by PHA, PPD, or monoclonal antibodies to T-cell surface antigens (anti-CD2 or anti-CD3). In vitro incubation with IL-2 did not increase lymphoblast transformation by anti-CD3 before RT but significantly increased after RT. In conclusion, we suggest that one of the fine mechanisms behind the RT-induced suppression of immune responsiveness of patients with lung cancer is a defect in IL-2 synthesis by lymphocytes.

Effects of radiation therapy on T-lymphocyte subpopulations in patients with head and neck cancer

Cellular immunity was assessed in 85 patients with head and neck cancer with monoclonal antibodies to lymphocyte surface antigens that identify total T cells, helper cells, and suppressor cells. The control group consisted of 22 healthy volunteers. Nine patients who had surgical procedures for benign diseases were also studied. Compared with the controls, the patients with cancer who received radiation therapy had a significant decrease in total lymphocytes, T cells, helper cells, suppressor cells, and decreased helper/suppressor cell ratio. Significant decreases in lymphocyte subpopulations were not detected in patients tested before treatment or in patients treated with surgery alone. The immune deficits observed were prolonged in duration, with some present in the patients studied up to 11 years after radiation therapy. This long-lasting immune depression may have relevance to tumor recurrences and second primaries in patients with head and neck cancer treated by radiation therapy and to attempts at increasing cure rates with adjuvant agents that improve immune reactivity.

T-cell abnormalities after mediastinal irradiation for lung cancer. The in vitro influence of synthetic thymosin alpha-1

The effects of mediastinal irradiation (RT) on the numbers and functions of purified peripheral blood T-lymphocytes from patients with locally advanced non-small cell lung cancer were evaluated. The patients were candidates for a randomized trial to evaluate the immunorestorative properties of synthetic thymosin alpha-1. Twenty-one patients studied before RT did not exhibit any significant difference in T-cell numbers or function compared to age-matched healthy subjects. However, 41 patients studied within 1 week after completing RT exhibited significant depressions of E-rosette-forming cells at 4 degrees C (E4 degrees-RFC)/mm3, E-rosette-forming cells at 29 degrees C (E29 degrees-RFC)/mm3, OKT3/mm3, OKT4/mm3, and OKT8/mm3 (P = 0.0001); total T-cell percentages (%OKT3, P = 0.01); and T-cell proliferative responses in mixed lymphocyte cultures (MLR) (P = 0.01) and to the mitogen phytohemagglutinin under suboptimal conditions (P less than or equal to 0.03). Nine patients studied before and after RT showed a significant increase in OKT4/OKT8 (P = 0.01) following RT. A short-term in vitro incubation with thymosin alpha-1 could enhance MLR of T-cells in 12 of 27 patients with post-RT abnormalities. In 13 patients who were treated with placebo, the RT-induced depression of T-cell numbers and function persisted for at least 3 to 4 months. In addition, in 12 patients progressive decreases developed in %E4 degrees-RFC, %OKT3, %OKT4, and OKT4/OKT8, which always preceded clinical relapse. This study indicates that mediastinal RT results in prolonged depletion of circulating T-cells, alterations of T-cell subset proportions, and intrinsic T-cell functional deficiencies. This patient population provides a uniformly immunosuppressed group of subjects with which to evaluate the immunorestorative effects of thymosin alpha-1 or other biologic response modifiers.

In vitro prostaglandin release from guinea pig parenchymal lung tissues is not stimulated by thymic peptides

Prostaglandins (PGs) have been demonstrated to both enhance and inhibit immune responses. As several chemically distinct serum and thymic polypeptide preparations have been shown to stimulate immunologic reactivity in several cell populations, animal models, or clinical patient trials, we have investigated the capacity of these hormone-like products from the thymus and blood to modulate PGs generation/release in normal parenchymal lung tissues of the guinea pig. Several concentrations of thymosin fraction 5, serum thymic factor, tuftsin or thymopentin, as well as histamine or A23187 (as positive controls) were exogenously applied to parenchymal lung fragments in vitro, and supernatants analyzed for PG content by radioimmunoassay. No alteration in PG levels (enhancement or suppression) from basal (spontaneous) release was found. These findings suggest that during a 30-min incubation, all four polypeptide immunomodulators were ineffective in eliciting an immediate response in the arachidonic acid cascade via the cyclooxygenase pathway.

Immunology of head and neck cancers

Despite the ever growing collection of data concerning the function of the immune system in patients with epidermoid carcinoma of the head and neck, the precise mechanism by which these tumors effect the body's surveillance against foreign antigen is as yet unidentified. If these specific immunological characteristics of the cancer cell can be identified, laboratory analysis of these "markers" could lead to detection and treatment of cancer in its earliest stages. Included in this chapter is a review of the embryological development of the immune system, a description of the components of the immune system and their responses to invasion by tumor antigen. Measurements of immuno responsiveness of the individual are important in determining the pretreatment state of immuno-competence and in predicting prognosis following treatment. Measurements of T-lymphocyte functions and their response to immuno-manipulations can also aid in predicting which patients will benefit from immunotherapy. Finally, categorization of the multiple forms of immunotherapy including active, specific and non-specific, and adoptive mechanisms are discussed. More recent methods of related immunotherapy trials will also be mentioned. As of this writing, the trials of immunochemotherapy have not produced any conclusive results due to the lack of multi-institutional trials and limited quantities of immunotherapeutic agents for these clinical trials.

[Investigations of unspecific immune reactivity in patients with head and neck carcinoma (author's transl)]

Unspecific cellular immune reactivity in 30 patients with squamous cell carcinoma of the head and neck was compared with those in 30 healthy controls. Assays were performed in vitro to evaluate the blastogenic response of lymphocytes to the mitogens PHA (phytohemagglutinin), Con A (Concanavalin A) and PWM (pokeweed mitogen) and to quantify T-rosette-forming lymphocytes. The in vivo assay used was the delayed cutaneous hypersensitivity reaction to DNCB (dinitro-chlor-benzene). Tests were performed in all patients every 4 weeks either for a total of 1 year or until death. Tumor patients were followed up to 5 years. Compared to healthy controls tumor patients demonstrated significant impairment of unspecific immune reactivity. Surgery, chemotherapy, and radiotherapy led temporarily to a further decrease of immune reactivity. There was no correlation between unspecific immune reactivity and tumor stage, course of the disease, and prognosis. It was not possible to give any useful statement for patients with squamous cell carcinoma of the head and neck by determining their unspecific immune reactivity.

Current status of thymosin research: evidence for the existence of a family of thymic factors that control T-cell maturation

Thymosin fraction 5 contains several distinct hormonal-like factors which are effective in partially or fully inducing and maintaining immune function. Several of the peptide components of fraction 5 have been purified, sequenced and studied in assay systems designed to measure T-cell differentiation and function. These studied indicate that a number of the purified peptides act on different subpopulations of T-cells (see Figure 1). Thymosin beta 3 and beta 4 peptides act on terminal deoxynucleotidyl transferase (TdT) negative precursor T-cells to induce TdT positive cells. Thymosin alpha 1 induces the formation of functional helper cells and conversion of Lyt- cells to Lyt 1+, 2+, 3+ cells. Thymosin alpha 7 induces the formation of functional suppressor T-cells and also converts Lyt- cells to Lyt 1+, 2+, 3+ cells. These studies have provided further evidence that the thymus secretes a family of distinct peptides which act at various sites of the maturation sequence of T-cells to induce and maintain immune function. Phase I and Phase II clinical studied with thymosin in the treatment of primary immunodeficiency diseases, autoimmune diseases, and cancer point to a major role of the endocrine thymus in the maintenance of immune balance and in the treatment of diseases characterized by thymic malfunction. It is becoming increasingly clear that immunological maturation is a process involving a complex number of steps and that a single factor initiating a single cellular event might not be reflected in any meaningful immune reconstitution unless it is the only peptide lacking. Given the complexity of the maturation sequence of T-cells and the increasing numbers of T-cell subpopulations that are being identified, it would be surprising if a single thymic factor could control all of the steps and populations involved. Rather, it would appear that the control of T-cell maturation and function involves a complex number of thymic-specific factors and other molecules that rigidly control the intermediary steps in the differentiation process.