You will be presented with a citation segment from the section of a research paper. Classify the intent behind this citation by choosing from one of the following categories:

- Method: Cites the paper for its methodology or procedure.
- Background: Cites the paper to provide background information.
- Result: Cites the paper for its findings or results.

Your answer should be a single word from the following list of options: ["Method", "Background", "Result"]. Do not include any other text in your response.

Citation sentence:

Cryopreserved PBMC from an HIV-1 infected individual, patient ZA159, who developed strong MPER specific antibody responses during disease progression (Liechti et al, in preparation), were obtained through the Zurich primary HIV infection (ZPHI) study [21].
Method