Fig 4. LdCen-/- immunization induces NO production by splenocytes along with IgG2a antibody response from the serum of virulent L. donovani challenged young and aged mice.

Leishmania Ag specific stimulation of NO synthase (NOS₂) in the splenocytes of naive, LdCen-/-immunized, naive challenged and LdCen-/- immunized challenged. The activity of NOS₂, indicated by the amount of released nitrite (NO) in the Ag-stimulated splenocytes supernatants (24h) was measured by the Griess reaction (A). ELISA measurement of IgG, IgG1, and IgG2a Abs in sera from the mice immunized with LdCen-/- parasites for 5-wk or naïve at 4-wk post challenge (B). The data presented are representative of two independent experiments with similar results. Mean and SEM of six mice in each group are shown. *p < 0.05, **p < 0.005. Black bar indicates young mice and white bar indicates aged mice.