Longitudinal cellular immune responses in asymptomatic and symptomatic Brugia malayi-infected Indian leaf monkey Presbytis entellus

TO investigate the cell-mediated immune (CMI) responses of the host during the development of acute filarial disease manifestations, we studied the se quential changes in CD4(+) and CD8(+) T-cell subsets, leukocyte migration i nhibition (LMI) response to Brugia malayi adult worm antigen, and concanava lin-A (ConA) and filarial antigen-induced lymphocyte transformation (LT) in the Indian leaf monkey (Presbytis entellus)-B. malayi model. Filarial infe ction was established in monkeys by subcutaneous inoculations of infective larvae (L-3) (700-1,250 L-3/monkey) in multiple doses, and the infected mon keys were categorized as symptomatic (Sym) and asymptomatic (Asym) dependin g on whether or not acute clinical manifestations were shown by them. In Sy m monkeys, LMI response to homologous adult parasite antigen was significan tly suppressed as compared to Asym monkeys. In Asym monkeys, LMI response V aried among the animals; 2 showed an increase throughout the study period a nd 2 showed suppression at different time points. When compared with Asym m onkeys, CD8(+) T cells in Sym monkeys showed a trend of significant increas e after day 180 postinoculation (PI). CD4(+) T cells remained within the no rmal range till day 300 (PI), after which they showed a marginal increase. ConA-stimulated LT was suppressed in Asym monkeys from day 60 PI. Antigen-s timulated LT was unresponsive in both Asym and Sym animals. Thus, the host' s LT response to ConA is suppressed in Asym animals, and alteration in CD8( +) T-cell number and LMI response in Sym monkeys may be involved in the dev elopment of the acute disease manifestations in this model.