Thymosin alpha 1 in myasthenia gravis

Thymic peptide hormones: basic properties and clinical applications in cancer

The manuscript will provide an in-depth and critical review of the nomenclature, biochemistry, biological properties, and a summary of published and on-going clinical trials with all reported thymic preparations, including both partially purified thymic factors (e.g., thymosin fraction 5, thymostimulin) as well as purified and synthesized thymic peptides (e.g., thymosin alpha 1, thymulin). Particular emphasis will be placed on which thymic peptides should be categorized as true hormones. In addition, the comparative biochemistry and biological activity in animals will be summarized and contrasted for all the currently available thymic factors. The effects, in vitro of thymic factors, on peripheral blood lymphocytes isolated from normal donors and patients with primary immunodeficiency disorders, autoimmune disorders, and neoplastic disorders will also be reviewed. Finally, a detailed critical summary of the clinical trials performed with each of the thymic preparations will be presented with an emphasis on treatment of patients with cancer.

Distribution of prothymosin alpha in rat tissues

A radioimmunoassay, using a rabbit antiserum directed against thymosin alpha 1, was employed to detect the presence of crossreacting peptides in rat tissues. Highest concentrations were present in thymus, but thymosin alpha 1 cross-reacting material was also detected in brain, liver, kidney, lung, and spleen, in amounts ranging from 15% to 65% of the quantities found in thymus. In each case, the major immunoreactive peptide, after extraction and purification by a procedure that avoids proteolytic modification, was identified as prothymosin alpha, a peptide containing approximately equal to 112 amino acid residues. Prothymosin alpha is believed to be the endogenous peptide from which thymosin alpha 1 and other fragments are formed by proteolytic modification during the preparation of thymosin fraction 5. No peptides corresponding in size and chromatographic behavior to thymosin alpha 1 were detected with the extraction procedure employed.

A prospective study of thymectomy and serum acetylcholine receptor antibodies in myasthenia gravis

Forty-seven consecutively presenting myasthenia gravis (MG) patients with generalized weakness were treated according to a standardized prospective protocol. All patients underwent a sternal splitting "total" thymectomy. Medical status before surgery was optimized by plasmapheresis without immunosuppression. Medications were avoided or discontinued whenever possible. All patients were improved. At the time of latest follow-up 83% were free of generalized weakness and 61% were on no medications. There was no significant change in Acetylcholine Receptor Antibody (AChR-AB) titer. The following conclusions were made: (1) thymectomy is an effective therapy for MG, (2) additional medications are not necessary in the majority of patients, and (3) a reduction in the AChR-AB titer is not essential for clinical benefit.

Imbalances in T-cell subpopulations in myasthenia gravis

Distributions of peripheral blood lymphocyte subpopulations and T-cell subsets were studied in 38 patients with myasthenia gravis (MG) and 23 healthy controls. T cells were detected by rosette formation with sheep red blood cells and B cells with erythrocyte-antibody-complement (EAC) complexes. T mu cells were identified by rosette formation of T cells with Ox RBC-IgM complexes, and T gamma cells with Ox RBC-IgG complexes. The means of total lymphocyte count and active T cell percentage were marginally significantly lower in MG patients than in normal controls (0.05 less than P less than 0.1). The mean percentage of T mu cells was higher in MG patients than in controls (50.2 +/- 11.8% vs. 38.5 +/- 15.3%, P less than 0.01), whereas that of T gamma cells in the former was lower than that in the latter (20.4 +/- 7.1% vs. 27.6 +/- 6.2%, P less than 0.001). Thus, the loss of regulatory suppressor T cells and the increase of helper T cells in the patients are in favour of regarding MG as an autoimmune disease. The fact that the percentage of T gamma cells was significantly decreased in MG patients after autologus serum incubation, and that no such a phenomenon was seen in normal controls, may suggest a possible role of serum factors in the pathogenesis of MG.