Table 5.

Comparison of the effect of control antibodies [mouse “anti-human IgG” antibody (isotype control)], anti-human leucocyte antigen (HLA) class Ia allele Abs, anti-HLA-E monospecific mAb Terasaki Foundation Laboratory (TFL)-033, and anti-HLA-E mAb TFL-037 (HLA-F- and G-non-reactive) versus intravenous immunoglobulin (IVIg)-mimetic anti-HLA-E monoclonal antibodies (mAbs) TFL-006s and TFL-007s on suppression of blastogenesis

CD4	Mean	SD	P2 value
Negative control mAbs (n = 3)
No PHA
Naive	3454	106
T lymphoblasts	263	14
With PHA
Naive	1099	48	<0·0004
T lymphoblasts	969	117	0·0005
mouse “anti-human IgG” antibody (isotype control)
Naive	1024	131	n.s.
T lymphoblasts	1758	84	n.s.
Iλ HLA-Ia (A11, A43) mAb ×2124 (source: Nadim/TFL)
Naive	924	11	0·02
T lymphoblasts	1758	84	n.s.
Iλ HLA-Ia mAb ×9123 (source: Nadim/TFL)
Naive	950	117	n.s.
T lymphoblasts	1435	276	n.s.
Iλ HLA-Ia mAb ×9133 (source: Nadim/TFL)
Naive	1032	54	n.s.
T lymphoblasts	1511	162	n.s.
TFL HLA-E mAbs (n = 3)
No PHA
Naive	3055	195
T lymphoblasts	254	18
With PHA
Naive	1099	48	0·0001
T lymphoblasts	969	117	0·0005
PHA +/TFL-007 (1/100)
Naive	1000	65	n.s.
T lymphoblasts	640	137	0·03
PHA +/TFL-006 (1/100)
Naive	1187	65	n.s.
T lymphoblasts	502	184	0·02
PHA +/TFL-037 (1/100)
Naive	1169	72	n.s.
T lymphoblasts	911	54	n.s.
PHA +/TFL-033 (HLA-E monospecific mAb) (1/100)
Naive	401	38	n.s.
T lymphoblasts	509	78	n.s.

All antibodies were obtained from culture supernatants, the CD4⁺ T lymphocytes from donor R. Treatment of cultures was with and without adding phytohaemagglutinin (PHA) (first two rows). The number of cells is shown for group 2 (T lymphocytes) and group 3 (T lymphoblasts) after exposing PHA-treated cells to the various control antibodies, and then to the TFL mAbs at 1/100 dilution. The values are expressed as mean ± standard deviation (s.d.) (n = 3) with two-tailed P-values for treatment with only PHA compared with no PHA, and with PHA plus mAb dilutions compared with only PHA. Note that both TFL-006a and TFL-007a decreased the number of PHA-activated T cells significantly while neither the control mAbs nor TFL-033, an HLA-E monospecific mAb, suppressed the blastogenesis. The data establish the importance of the Fab portion of the antibody in binding to the shared peptide sequences exposed on the open conformers of HLA class Ia and Ib alleles. The Fc portions of these and other mAbs did not suppress proliferation. These data also establish that open conformers of HLA class I may act as inhibitory ligands for activated T cells. See Table Ib for HLA-reactivities of the TFL-mAbs. 1λ refers to the original source of mAb as One Lambda, Inc.