Cattle Infected with Bovine Leukaemia Virus may not only Develop Persistent B‐cell Lymphocytosis but also Persistent B‐cell Lymphopenia

Abstract

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.

Dinámica de la Leucosis Bovina en el ganado criollo Hartón del Valle en infección natural

“…Algunos autores señalan que entre el 30% y el 70% de los animales infectados con el VLB desarrollan linfocitosis persistente (LP + ) (Dequiedt et al, 1999;Beyer et al, 2002;Chamizo, 2005;Rama, 2009 -realizan apoptosis ex vivo, además, que la respuesta de los linfocitos a la apoptosis puede estar relacionada con factores del hospedero. Rama, (2009) aclara que el recuento celular está influenciado por la edad siendo mayor en animales jóvenes.…”

“…La leucosis bovina enzoótica (LBE), es una enfermedad infecciosa producida por un retrovirus, el virus de la leucosis bovina (VLB), que afecta las células de la línea linfoide, los linfocitos "B" (Beyer et al, 2002; Baruta et al, 2011;). Es una enfermedad linfoproliferativa y se caracteriza por presentar linfocitosis persistente (LP) que se manifiesta con un incremento sostenido del número absoluto de linfocitos en la corriente sanguínea la cual aparece con una frecuencia de entre el 30 y 70% de los animales infectados; tumores (linfosarcoma o linfoma maligno) en los bovinos mayores a 3 años con una frecuencia de ocurrencia de entre 0.1 y 10% y una forma en la cual los animales tienen anticuerpos (anti-VLB) sin linfocitosis persistente, ni lesiones tumorales condición conocida como fase Aleucemica (Chamizo, 2005;Cadavid 2012).…”

Enzootic bovine leukosis and the risk to human health

“…BLV (Retroviridae family; Orthoretrovirinae subfamily, Deltaretrovirus genus) is an exogenous retrovirus, responsible for EBL, which is the most common neoplastic disease in cattle worldwide (Schwartz and Levy, 1994;Dequiedt et al, 1999;Beyer et al, 2002;Moratorio et al, 2013). BLV is related to human Tlymphotropic virus types 1, 2 and 3 (HTLV 1, 2 and 3) and primate T-lymphotropic virus types PTLV 1, 2 and 3 (Gelmann et al, 1983;Tanaka et al, 1990;Heenemann et al, 2012).…”

Nested polymerase chain reaction (nPCR) based diagnosis of bovine leukemia virus in Panama

“…The bovine leukemia virus (BLV; family Retroviridae; subfamily Orthoretrovirinae, genus Deltaretrovirus) is an exogenous retrovirus that causes enzootic bovine leukosis (EBL), the most common malignancy of cattle worldwide (Schwartz et al, 1994;Dequiedt et al, 1999;Beyer et al, 2002;Moratorio et al, 2013). This virus is related to the human T-lymphotropic virus types 1, 2 and 3 (HTLV-1, -2 and -3) and to the primate T-lymphotropic virus types 1, 2 and 3 (PTLV-1, -2 and -3) (Gelmann et al, 1983;Tanaka et al, 1990;Heneeman et al, 2012).…”