Reactions of peripheral blood mononuclear cells (PBMC) of camels with monoclonal antibodies against ruminant leukocytes.

The particular immune system of the camel has been but little investigated. In this work circulating camel peripheral blood mononuclear cells (PBMC) were studied by flow cytometry. Monoclonal antibodies (mAbs) raised against ruminant leukocytes were used for the detection of cell surface antigens. Monoclonals to T-cell markers, CD4 (CACT138A) and CD8 (CACT80C), exhibited no reactivity towards camel PBMC in contrast to their reactivity to PBMC of other ruminant species and those of cattle in particular. A relatively high percentage (29.1+/-8.9%) of camel PBMC reacted with a non-immunoglobulin cell surface marker, B-B2, comparable to the reactivity of bovine PBMC. The B-B7 cell marker revealed 22.4+/-10.0% of reactive camel PBMC while the CD45 leukocyte common antigen was identified only on 19.4+/-3.1% of camel PBMC as compared to 74.7+/-4.9% for bovine PBMC. IgM (PIg45A) was detected on 9.1+/-1.4% of camel PBMC and on 46.6+/-19.5% of the bovine PBMC. Double fluorescent labeling with two B-cell markers and an anti-ruminant lambda light-chain mAb revealed 7-9% of cells bearing both B and lambda L-chain markers. Light chain reactivity was also assessed using an anti-goat F(ab')(2) antiserum. The values obtained, 14.3+/-5.8% for the camel and 47.8+/-2.7% for the cattle, are close to the values observed for surface IgM. These data suggest that camels, like other ruminants, possess L-chain bearing cells of the B-cell lineage. However, in the camel, Igs are different in that in addition to regular four chain Igs, about 65% of them possess two heavy chain Igs devoid of light chains. Because different sets of V(H) gene segments are used by four and two chain Igs, it is possible that there might be two lineages of B-cells each secreting a different form of antibodies.

Experimental infection of calves with bovine leukemia virus (BLV): an applicable model of a retroviral infection.

An experimental model of chronic infection with bovine leukemia virus (BLV) was established in young calves within a relatively short time. In the sera of all infected calves, precipitating antibodies were detected within 5 weeks after infection but upon disease progression pattern of cellular profiles varied. Three calves exhibited transient lymphocytosis 3-5 weeks after infection, two became persistent lymphocytotic (PL+) by that time and one stayed non-lymphocytotic (PL-) for 11 weeks and became PL+ after 4.5 months. Eventually all infected calves became PL+ by the end of the experiment, 6-12 months after infection. Increase of total counts of peripheral blood mononuclear cells (PBMC) related to polyclonal expansion of B-cells. The latter was assessed in all infected calves where the expansion of CD5-bearing cells (B+ CD5+) correlated with increase or decrease of total PBMC counts. Other cell populations such as CD4 and CD8 were also affected. Percentages decreased by 5 weeks after experimental infection to about half their original values though actual cell numbers stayed relatively stable. The experimental model we established compared well with field cases of naturally BLV-infected cattle and thus permitted the investigation of the disease at early stages of infection.