Figure 5. In IgD⁺ mult-HCL and IgD⁺ s-HCL anti-sIgD stimuli do not trigger apoptosis.

For IgD+ mult-HCL Case 13 (functional isotypes for ERK1/2 phosphorylation: D⁺⁺, G⁺, M⁺, λ⁺⁺) material was available to evaluate stimulation with soluble goat F(ab’)₂ anti-sIgD/λ antibodies or anti-sIgA as control (isotype not functional). Panel A shows representative data from 1 of 2 replicate experiments assaying apoptosis in CD19^HICD11c^HICD103⁺ tumor cells following stimulation. Anti-sIgD stimulation did not induce apoptosis as compared to the non-functional isotype control. Stimulation with soluble anti-sIgM did induce a low but significant increase in apoptosis as this isotype is functional. This lack of apoptotic effect in response to IgD stimulation was further investigated in a single sIgD+ve s-HCL Case 15 (phenotype summarised in Panel C). Stimulation via sIgD or slgλ in this s-HCL case did not induce apoptosis of CD19^HICD11c^HICD103⁺ tumor cells either in response to soluble (Panel B) or immobilised anti-sIg (data not shown). Data were analysed in PRISM using student’s t-test with Welch’s correction. P-values are summarised as ns>0.05, *0.01–0.05, **0.01–0.001, ***0.001–0.0001, ****<0.0001.