EDITORIAL

Cytokines - a way towards better animal health Our understanding of the immune response has taken a

quantum leap forward with the identification of a group of regulatory proteins, now known collectively as lymphokines or, more accurately, as cytokines. The cytokines act as the soluble messengers between the diffuse network of cells that make up the immune system in much the same way that hormones integ- rate the activities of their target organs. These proteins were originally defined by their biological activities (usually within in-vitro culture systems) and given designations such as “T cell growth factor”, “B cell differentiative factor” or “granulocyte colony-stimulating factor”. Purification of these proteins to obtain homogeneous preparations was often difficult, and as these proteins can have multiple target cells and multiple bio- logical activities, their function and relevance within an immune response was difficult to define.

Resolution of the quagmire of factors and activities has been largely due to the identification and cloning of the cytokine genes. Expression of the cloned genes has provided sufficient quantities of purified protein for use in in-vitro and in-vivo systems. The cloned cytokines are designated either as interleukins (currently interleukins 1 to 7 have been defined), which usually are produced by T lymphocytes and stimulate the differentiation of prolifer- ation of other T or B lymphocytes or colony-stimulating factors which promote the differentiation of haemopoietic stem cells along a particular differentiation pathway, or Y -interferon.

Much of the characterisation of cytokine activities has been performed in the mouse and, more recently, in the human system. Some cytokine activities are able to cross the species barrier, but many are species-specific For this reason, there is growing interest in identifying and cloning cytokine genes from livestock species. The gene for bovine Y -interferon has been already cloned and

in this issue of AVJ, Tony Radford and his co-authors from CSIRO Division of Animal Health in Parkville describe the cloning and sequencing of the ovine Y-interferon gene, using the new recombinant DNA technique of polymerase chain reaction.

So, how can the cloning of ovine and bovine cytokine genes benefit the livestock industries? Undoubtedly, the first uses of cytokines expressed from these cloned genes will be in research laboratories. A readily available supply of pure cytokine will allow the elucidation of their role in the clearance of infectious agents and parasites from animals and will aid in the development of assays to measure their presence. However, there is already evidence that cytokines have potential health benefits. Interleukin 2, which stimulates the proliferation of T lymphocytes during an immune response, promotes the clearance of virus from animals with depressed immunity, is associated with adjuvant affects in vaccines and, in man, is used successfully in the treatment of some forms of cancer. Bovine Y -interferon has been used to prevent experimentally-induced shipping fever in cattle and in the treatment of neonatal diarrhoea. A sensitive sandwich enzyme immunoassay for bovine YI-interferon also has been developed recently and used for the diagnosis of tuberculosis in cattle.

Although much still needs to be done, the time is approaching when our knowledge of immune function will be such that we will be able to design vaccines intelligently and to use cytokines, produced in vitro by recombinant DNA technology and drugs to manage the immune responsiveness to the animals in our care.

ME Andrew (Accepted for publication 24 September 1990)

. . . Changes in the Journal . . . As members of the AVA and subscribers to this Journal are

aware, scientific journals are expensive to publish and to buy. For a journal to maintain standards, indeed to survive, in times of change needs diligence and adaptability. A ,,-,inor change in layout of the contents page in this issue may have caught your eye. In the next issue, the Journal will begin using a computerised system that will typeset manuscripts from discs - a major change that should pass unseen. These changes, by increasing revenue and cutting costs, will contribute to ensuring the continued financial stability of the Journal.

The Journal now requires all accepted manuscripts on word processor discs. Advice will be sent with the letter of acceptance to authors to help them adapt the format of their Paper. This will not be an onerous task. Arrangements will be made for authors without access to necessary facilities. Authors will be sent page proofs instead of galley proofs for scrutiny before publication.

Meanwhile, what will not diminish is the endeavour of the Editorial Committee both to maintain the high standard of integrity and quality of the content of this Journal and to ensure its continued relevance to veterinary science in Australia.

Australian Veterinary Journal, Vol. 68, No. 3, March, 1991 81