Appeal No. 2005-1511
Application No. 09/879,398
only recognize foreign antigens that are bound to specialized molecules
found on virtually all cells. Thus, most infected cells of the body may
serve as CTL targets [Bell, p. 3].
***
Leukocytes express a variety of surface molecular markers that
provide a basis for distinguishing progenitor and mature cells. The
clusters of differentiation (CD) numbering system has been devised to
provide a universal means for identifying various types of leukocytes.
Surface markers on leukocytes are antigenic and can be bound by
monoclonal antibodies. By agreement, CD numbers have been assigned
to those surface markers to which are bound antibodies having similar
specificity characteristics. For example, T cells were found to be
distinguished from B cells by their ability to bind to sheep erythrocytes via
the CD2 surface marker. Thus, CD2 is a marker for T cells. Of course,
the primary surface marker distinguishing T cells is the T cell antigen
receptor (TcR), which forms a complex with another T cell specific surface
marker, CD3. Most T cells express a T cell receptor composed of an
alpha (α) chain and a beta (β) chain (TcRαβ), while a small subset
express a TcR composed of gamma (γ) chain and a delta (δ) chain
(TcRγδ) [Bell, p. 7].
With regard to T cells specifically, the vast majority of T cells can be
subdivided into either CD4+ or CD8+ cells, i.e., T cells which express
either the CD4 or CD8 marker. CD4+ T cells are also known as helper T
cells, and function to positively or negatively influence the immune
response of B cells and other T cells. CD8+ T cells are called cytotoxic or
killer T cells. Suppressor T cells, which are activated by CD4+ cells, also
are CD8+. Other lymphocytes which exhibit a cytotoxic function include
natural killer (NK) cells and lymphokine activated killer (LAK) cells, which
cells are both CD4- and CD8-, cytokine induced killer cells (CIK) which co-
express CD56, CD3, TcRαβ and CD8, and TcRγδ+ cells which are either
CD4-/CD8- or CD4-/CD8+ [Bell, para. bridging pp. 7-8].
According to the appellant, he
. . . previously reported an improved survival advantage for patients who
develop an increased number of γδ+ T cells following allogenic BMT [bone
marrow transplant]. (Lamb, et al., J Hematotherapy, 1996 - of record).
Appellant posited that this increase played a role in graft-versus-leukemia
effect. Accordingly, he isolated the leukemia cells and phenotypically
characterized them. He was then able to replicate in vitro the process
which presumably occurs in vivo: intentionally selecting for γδ+ T cells in
the donor material and subsequently activating them through exposure to
the recipient’s own leukemia blast cells so as to render the activated γδ+ T
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