Cattle infected with bovine leukaemia virus may not only develop persistent B-cell lymphocytosis but also persistent B-cell lymphopenia.
We investigated the distribution of B and T cells in the peripheral blood of haematologically inconspicuous (non-persistent lymphocytotic, PL-) cattle infected with the bovine leukaemia virus (BLV). Flow cytometric data were obtained from six PL- cattle and compared with six age-matched animals with persistent lymphocytosis (PL+) and five non-infected healthy controls (BLV-). In the PL- group, the percentage and number of surface immunoglobulin-positive (sIg+) B cells were significantly reduced. Whereas in BLV-cattle, about 40% of the peripheral blood lymphocytes (PBL) were sIg + and 24% were sIgM + B cells. In the PL- group, less than 20% of the PBL were sIg+ and sIgM+ B cells. Only 5% of the PBL co-expressed sIgM+ and CD5+ versus 16% in BLV-. This decrease was persistent over 3 years and predominantly affected: (i) B cells that did not express sIgM; (ii) sIgM + B cells co-expressing CD5 and CD11b; and (iii) equally both lambda- and K-type light chain B-cell subpopulations. In contrast, the number of all circulating lymphocytes, CD5- and CD11b- sIgM+ B cells and CD2+ T cells did not differ. In PL+ animals, about 75% of the PBL were sIgM+ CD5+ B cells. These cells were of polyclonal origin, as light chains of the lambda- and K-type were expressed in a ratio of 4:1 (57.7% of PBL lambda+, 14% kappa+) as in BLV- animals (33.6% of PBL lambda+, 8.7% kappa+). In PL+ cattle the absolute number of B-cells and, therefore, their relative percentage is significantly increased. For this reason, even in case of absolutely increased T-cell numbers, the relative percentage of T-cells could be lower than in normal controls. The cause for the observed B cell decrease in PL- cattle is unknown, but it can be assumed that cytotoxic T cells are involved in this B-cell lymphopenia.
Beyer
J
J
Institute of Infectology, Federal Research Centre for Virus Diseases of Animals, Friedrich-Loeffler-Institutes, Insel Riems, Germany. joerg.beyer@rie.bfav.de
Köllner
B
B
Teifke
J P
JP
Starick
E
E
Beier
D
D
Reimann
I
I
Grunwald
U
U
Ziller
M
M
D000818:Animals; D000911:Antibodies, Monoclonal; D016175:B-Lymphocyte Subsets / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D016022:Case-Control Studies; D002417:Cattle; D004279:DNA, Viral / Q000302:isolation & purification; D016583:Enzootic Bovine Leukosis / Q000150:complications / Q000821:virology*; D005434:Flow Cytometry / Q000662:veterinary; D001909:Leukemia Virus, Bovine / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000276:immunology; D008218:Lymphocytosis / Q000150:complications / Q000662:veterinary; D008231:Lymphopenia / Q000150:complications / Q000662:veterinary; D051379:Mice; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011947:Receptors, Antigen, B-Cell; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D004279:DNA, Viral; D011947:Receptors, Antigen, B-Cell