Thymic humoral factor .gamma.2: purification and amino acid sequence of an immunoregulatory peptide from calf thymus

Abstract

Thymic humoral factor gamma 2 (THF-gamma 2), an octapeptide essential for immune regulation, was purified from calf thymus. The purification of THF-gamma 2, monitored in vitro and in vivo in mouse splenocyte proliferation assays, was achieved by gel filtration of low molecular weight thymus extracts followed by ion-exchange chromatography and sequential reversed-phase high-performance liquid chromatography. The process yielded 5 micrograms of THF-gamma 2/1000 kg of thymus tissue. The concentration of THF-gamma 2 required for augmentation of lymphocyte proliferation and interleukin 2 production was 5 ng/mL in vitro and 10 ng/kg per mouse in vivo. THF-gamma 2 has the amino acid sequence Leu-Glu-Asp-Gly-Pro-Lys-Phe-Leu. The proposed structure has been confirmed because a peptide was synthesized on the basis of this sequence that showed activity identical with that of the biological molecule. It shows no homology to the amino acid sequence of other thymic hormones nor is it part of any peptide or protein of known sequence. THF-gamma 2 retains essentially all of the biological activity of the thymus extract from which it is derived.

The Immunoendocrine Thymus as a Pacemaker of Lifespan

“…It has all the biological activities of THF. This is a specific sequence that does not show homology with other thymic or non-thymic hormones [22]. A few nanograms of it enhances the frequency of mitogen responsive T cells in the thymus or the spleen, and positively influences T helper cell functions [23], targeting first of all the younger cell population [24].…”

SYNTHESIS AND IMMUNOLOGICAL EFFECT OF THYMIC HUMORAL FACTOR-γ 2 ANALOGUES

“…Examination of the cellular immunocompetence of these patients revealed a significant decrease in blast formation by PHA. 3 H-Thymidine incorporation values of these patients were 12168, 11187, and 12491 cpm, respectively (normal values 40346741594 cpm).…”

“…The thymic humoral factor (THF)-g 2, an octapeptide essential for immune regulation, was isolated from calf thymus by Burnstein et al [3] THF-g 2 has the amino acid sequence: H-Leu-Glu-Asp-Gly-Pro-Lys-PheLeu-OH and shows no similarity to those of other thymic hormones.…”

A Thymic Metallo-Peptide Influences Lymphocyte, Monocyte and Thymocyte Responses

“…Divalent cations, polypeptides and basic proteins have all been proposed to be natural mitotic stimulants, both in vivo and in vitro, serving to initiate cell division [5][6][7][8]. The thymic octapeptide Leu-Glu-Asp-Gly-Pro-LysPhe-Leu (L 1 EDGPKFL 8 ) has been implicated in augmenting T-cell functions, such as the response to T-cell lectins and mixed lymphocyte reactions; it also increases interleukin-2 production by T-cells [9]. However, the reported concentration range in which it operates in vitro is very broad.…”