Cytotoxic effector cells against HLA antigens in strong linkage disequilibrium: identification of a strong, new CML determinant

A cloned cytotoxic T-lymphocyte (CTL) line recognizing a subtype of HLA B27

The lymphoblastoid cell-line JY (HLA-A2,2;B7,7;C-; DR4,w6) was used to stimulate T cells from donor HG (HLA-A2,w23; B40,w44; Cw4; DRw6,7). Cloned CTL line were obtained by limiting dilution after tertiary stimulation. Strong cytotoxic activity on stimulator cells was found with all CTL clones obtained. One of the clones (HG-31 recognized a subtype of the HLA-B7 antigen. In this paper, we describe another long-term cloned CTL line (HG-61). This line, when tested on a panel of 107 target cells from unrelated individuals, recognized a subtype of HLA-B27 (B27 "K"). There was no significant association with any other HLA antigen. The cloned CTLs were T8+ and their cytotoxic activity could be blocked by the monoclonal antibody W6/32 which recognizes a framework determinant on HLA-A, -B, and -C molecules. In families, reactivity with cells of the CTL line (HG-61) segregated with HLA. It is concluded that the CTL line interacts with an antigenic determinant shared between the HLA-B7 antigen and JY and the subtype of HLA-B27 (B27 "K"), or detects products of a gene closely linked to HLA-B, not revealed by present-day serology.

Differential recognition of the serologically defined HLA-A2 antigen by allogeneic cytotoxic T cells. II. Definition of three HLA-A2 subtypes by CTLs

A comprehensive analysis of human alloimmune cytotoxic T lymphocytes (CTLs) specific for the HLA-A2 antigen identified 11% of HLA-A2 positive cells as outliers. In total, 11 unrelated serologically indistinguishable, but distinguishable by cell-mediated lympholysis (CML) HLA-A2 positive outlier cells were identified. The outlier cells could be subdivided in two subgroups according to reactivity patterns obtained with CTLs directed against the HLA-A2 antigen of outlier cells and their inhibitory capacity in specific competitive inhibition experiments. Thus, the serologically defined HLA-A2 specificity can be divided into at least three subtypes using CTLs specific for the HLA-A2 antigen. Moreover, CTLs specific for an HLA-A2 subtype could be induced when responder cells expressed a different HLA-A2 subtype antigen. On the basis of several family studies, we conclude that the subtype HLA-A2 antigens are inherited in a codominant way.

Differential recognition of the serologically defined HLA-A2 antigen by allogeneic cytotoxic T cells. I. Population studies

Human alloimmune cytotoxic T cells, sensitized selectively against the HLA-A2 antigen, were tested on a panel of selected target cells. Five HLA-A2 positive outlier cells could be identified. These outlier cells were only weakly lysed by HLA-A2 specific CTLs, although they were serologically indistinguishable from the other HLA-A2 positive, strongly lysed target cells. Furthermore, it was found that the outlier cells were poor cold target inhibitors in contrast to the other HLA-A2 positive target cells, which showed adequate inhibition of specific lysis of HLA-A2 positive target cells. Population studies indicate that the frequency of such HLA-A2 outlier cells may be approximately 10%.

Differential behavior of cytotoxic effector cells against HLA antigens in strong genetic linkage disequilibrium

Five sets of cytotoxic effector cells were generated, using haplo-identical, first degree relatives in five different families, against the HLA-A3; B7 serological determinants combined with different DR antigens. When tested against a panel of cells bearing combinations of the HLA-A, -B and -DR antigens it was shown that the HLA-B7 antigen was as strong a CML target determinant alone as it was in the presence of HLA-A3. The strength of the HLA-A3 antigen as target determinant varied. With effector cells primed to the HLA-A3; B7; DR2 haplotype, the A3 antigen alone behaved as a weak target determinant. When the same target cells were tested with the effector cells generated against HLA-A3; B7 without DR2, the A3 antigen behaved as a strong target determinant. A number of target cells lacking the serologically detectable HLA determinants present on the sensitizing HLA haplotype were identified as being killed by specific effector cells. These data suggest either a number of new CML target determinants controlled by different loci or the presence of a single, new locus with multiple alleles controlling CML targets.