Toxicity of Aβ wild type and Aβ G37L peptides on Neuro 2a cells. Relative viability of Neuro 2a cells after treatment with Aβ wild type and Aβ G37L peptides for 24 hours, either singly or in various combinations. Viability was measured by the MTT assay and normalized to the vehicle-treated control cells. A. Neuro 2a cells were treated with 4 μM Aβ wild type that had been mixed with from 0-4 μM Aβ G37L for 20 min at RT before addition to the cells. The viability of each mixture was significantly different from that of Aβ wild type alone, and there was no significant difference in the viability of the vehicle control and an equimolar mixture of Aβ wild type and Aβ G37L (Student's t-test). Overall, Aβ G37L mitigated the toxicity of Aβ wild type in a linear dose dependent manner (R2 = 0.98). B. Neuro 2a cells were treated as described above with 4 μM Aβ wild type and/or 4 μM Aβ G37L. Note that the ability of Aβ G37L to inhibit Aβ wild type toxicity is lost when these peptides are oligomerized separately before addition to the Neuro 2a cell culture. (* P < 0.05, NS = not significant).