Isolation of various canine leucocytes and their characterization by surface marker analysis.

Various techniques were used to separate canine peripheral blood leucocytes into populations enriched in lymphocytes, polymorphonuclear leucocytes, phagocytic mononuclear cells (monocytes) and macrophages. Surface markers on each cell population were determined by rosette formation. Fc receptors for IgG and complement receptors (C3b and C3d) were present on PMN, monocytes, macrophages as well as on a sub-population of lymphocytes. Purification of the lymphocytes into T-and B-cell-enriched populations revealed that these receptors were present only on the B lymphocytes and not on the T lymphocytes. In addition, a third lymphocyte population, which did not possess surface immunoglobulin, and Fc receptor but not the complement receptor. None of the cell populations exhibited C4 complement receptors or Fc receptors for IgM. When different cell populations were tested for their ability to form rosettes directly with human type 'O' red blood cells it was found that most populations could rosette, suggesting that this technique could not be used as a specific marker for canine T lymphocytes.