Date of issue: 
The knowledge concerning cell surface markers and immunophenotypes of lymphocytes in different animal species opens possibilities in veterinary laboratory diagnostics. The human CD antigens do not always correspond to surface markers found on animal lymphocytes. Therefore, a close follow-up on research developments on new CD antigens and their corresponding monoclonal antibodies is important in veterinary laboratory diagnostics. A detailed description of known ruminant CD antigens is available. Thorough knowledge of clusters of differentiation is particularly important in the ruminant due to emerging diseases and difficulties in eliminating the already existing ones. Ruminant lymphocytes make up 45-75% of the total leukocyte population. CD45 is the common leukocyte antigen, however, it is absent from ruminant WC1+ lymphocytes and monocytes. Ruminant T cells are mainly identified by the TCR molecule, with TCR-1 (g and d) making up 60% of all T cells. Other T cell surface antigens are CD1, CD2, CD5, CD4, CD6, CD8 and WC1. In the ruminant, the CD4/CD8 index in peripheral blood is 1,53 and in milk it is 0,85, but fluctuates during lactation. WC1+ (CD4-CD8- TCR gd-) lymphocytes account for 40% of the total T cell population in young ruminants. Cell surface bound IgM and other molecules not related to those found on human lymphocytes such as WC3 (CD21-like), WC4 (CD19), WC6 (present on B and CD2+ cells but not on WC1 and thymocytes) and WC10 (on B and CD2+ cells but not present on monocytes, granulocytes and WC1 cells). Activation markers on both T and B cells are IL-2R (expressed after TCR-ab+ activation) and CD25 (highly expressed on WC1). CD1, CD45 isoforms and L-selectin receptors act as cell maturation markers. The immunophenotype of bovine peripheral blood NK cells is CD4-CD5- CD6-WC1- while that of LAK cells is CD2+CD4-CD8-.
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The Editorial Board
Andrzej Łukaszyk - przewodniczący, Zofia Bielańska-Osuchowska, Szczepan Biliński, Mieczysław Chorąży, Aleksander Koj, Włodzimierz Korochoda, Leszek Kuźnicki, Aleksandra Stojałowska, Lech Wojtczak

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Katedra i Zakład Histologii i Embriologii Uniwersytetu Medycznego w Poznaniu, ul. Święcickiego 6, 60-781 Poznań, tel. +48 61 8546453, fax. +48 61 8546440, email:

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