Conditioned inhibition of antibody response and CD4 positive cells.

Animals were assigned to three experimental groups, conditioned (cyclophosphamide-glucose treatment; C group), non-conditioned (cyclophosphamide-commercial pellet treatment; NC group) and placebo (saline solution-glucose treatment; P group). The three groups were injected intraperitoneally (i.p.) with sheep red blood cells. An hemagglutination assay according to standard procedures was performed along with the flow cytofluorometric analysis of leukocyte surface antigens CD4, CD8 and CD45. C group consumed less food on Days 3 and 6 than on Day 0, NC animals showed no changes in food consumption throughout the experimental period, whereas an increasing trend was observed for P animals. The proportion of T lymphocytes expressing CD8 and CD45 did not differ significantly among C, NC and P groups. Group C showed the lowest proportion of T lymphocytes bearing CD4, whereas Group P displayed the highest. The antibody response was lower in the Group C than in the groups NC and P. We conclude that, although the mechanisms by which humoral conditioned immunosuppression occurs in mice is still unknown, a reduced T helper-mediated activation of B-cells may play an important role in producing conditioned humoral response.