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Monoclonal antibodies against CD2 cell determinants involved in interactions between T cells and accessory cells
Abstracts
107 with various doses of PBL or human B cell lines. Lymph node or spleen cells were assayed for a secondary proliferative response against a panel of different target cells with various D R haplotypes (DR1-7). O u r results showed a positive cellular response when the target cells expressed human M H C class II antigens on their surface. N o response was obtained with D R negative human T cell or other xenogeneic target while BALB/c mice respond to Marmoset cell lines which share cross-reactive epitopes with human D R molecules. In addition, purified D R molecules (as controlled by 2-D gel) were obtained by immunoadsorbant from total extracts of these cells and further injected into mice. Such soluble D R antigens, with doses corresponding to 3 x 10 e' cell extracts were perfectly able to stimulate a murine response. In a secondary response, murine T cell proliferate similarly with the original H L A - D R homozygous B cell line and also with several others of different hapiotypes. Both cells and soluble antigens gave the same pattern of response when injected into mice. This pattern is not clearly related to allogeneic determinants on D R molecules. Comparison between allogeneic and xenogeneic secondary MLR and blocking studies with various a n t i - H L A - D R M o A b indicate that different polymorphic determinants were involved in stimulating human and murine T cells.
MONOCLONAL ANTIBODIES AGAINST CD2 CELL DETERMINANTS INVOLVED IN INTERACTIONS BETWEEN T CELLS AND ACCESSORY CELLS. Diana D. Friberg, Linda K. Myers, Edward J. Ball, and Peter Stasmy; Departments of Internal Medicine and Pediatric< Uniz,er~i(~ of Texas Health Science Center a t Dallas, Southwestern Medical School, Dallas T X In addition to the T cell receptor for antigen, a number of other molecules on T cells or accessory cells have been shown to be involved in the triggering of T cell responses. We have generated several murine monoclonal antibodies that inhibit T cell responses to a variety of stimuli. Eight antibodies obtained in four separate fusions were found to react only with T cells by complement-mediated cytotoxicity or indirect immunofluorescence. Four of these antibodies were found to inhibit T cell rosette formation with sheep erythrocytes. Lysostripping experiments with antibody O K T 1 1 indicated that each of these four antibodies reacted with the same or associated surface molecules, presumably CD2 (LFA-2, T11, Leu5). H o w e v e r , the different CD2-reactive antibodies were found not to be entirely equivalent in functional assays. One antibody, M P T 3 1 - B G 4 , was less effective at inhibiting T cell rosettes (64.3 +- 11.3% in 7 experiments) than the three other anti-CD2 antibodies or O K T l l (99.4 -+ 1.7% in 8 experiments). When tested for the ability to inhibit T cell proliferative responses to an optimal concentration of P H A , M P T 3 1 - B G 4 was more inhibitory (35.5 -+ 3.6% in 6 experiments) than the other antibodies ( 0 . 2 - 1 8 . 8 % inhibition). Each antibody inhibited P W M responses of T cells, but M P T 3 1 - B G 4 was the most inhibitory (79.8 -+ 1.4% vs. 2 8 . 6 - 5 2 . 8 % ) . In contrast, the ability o f M P T 3 1 - B G 4 to inhibit tetanus toxoid responses (34.2 -+ 10.7%) was less than that observed with the other anti-CD2 antibodies ( 4 8 . 3 - 7 4 . 5 % inhibition). It was shown, using cloned alloreactive T cell lines, that individual T cells have different degrees of sensitivity to inhibition by the M P T 3 1 - B G 4 antibody. O f 12 clones tested, five were strongly inhibited by M P T 3 1 - B G 4 ( 4 0 . 0 - 5 9 . 8 % inhibition), while seven were much less affected ( 0 - 2 1 % ) . These results suggest that different T cell clonotypes may be more or less dependent on additional interaction molecules such as CD2. Whether this correlates with specificity or functional attributes of the individual T cell is being investigated. The differential functional activity of the various anti-CD2 antibodies might be related either to avidity of the interactions or possibly to a relationship to a functional epitope(s) of the CD2 molecule.
107 with various doses of PBL or human B cell lines. Lymph node or spleen cells were assayed for a secondary proliferative response against a panel of different target cells with various D R haplotypes (DR1-7). O u r results showed a positive cellular response when the target cells expressed human M H C class II antigens on their surface. N o response was obtained with D R negative human T cell or other xenogeneic target while BALB/c mice respond to Marmoset cell lines which share cross-reactive epitopes with human D R molecules. In addition, purified D R molecules (as controlled by 2-D gel) were obtained by immunoadsorbant from total extracts of these cells and further injected into mice. Such soluble D R antigens, with doses corresponding to 3 x 10 e' cell extracts were perfectly able to stimulate a murine response. In a secondary response, murine T cell proliferate similarly with the original H L A - D R homozygous B cell line and also with several others of different hapiotypes. Both cells and soluble antigens gave the same pattern of response when injected into mice. This pattern is not clearly related to allogeneic determinants on D R molecules. Comparison between allogeneic and xenogeneic secondary MLR and blocking studies with various a n t i - H L A - D R M o A b indicate that different polymorphic determinants were involved in stimulating human and murine T cells.
MONOCLONAL ANTIBODIES AGAINST CD2 CELL DETERMINANTS INVOLVED IN INTERACTIONS BETWEEN T CELLS AND ACCESSORY CELLS. Diana D. Friberg, Linda K. Myers, Edward J. Ball, and Peter Stasmy; Departments of Internal Medicine and Pediatric< Uniz,er~i(~ of Texas Health Science Center a t Dallas, Southwestern Medical School, Dallas T X In addition to the T cell receptor for antigen, a number of other molecules on T cells or accessory cells have been shown to be involved in the triggering of T cell responses. We have generated several murine monoclonal antibodies that inhibit T cell responses to a variety of stimuli. Eight antibodies obtained in four separate fusions were found to react only with T cells by complement-mediated cytotoxicity or indirect immunofluorescence. Four of these antibodies were found to inhibit T cell rosette formation with sheep erythrocytes. Lysostripping experiments with antibody O K T 1 1 indicated that each of these four antibodies reacted with the same or associated surface molecules, presumably CD2 (LFA-2, T11, Leu5). H o w e v e r , the different CD2-reactive antibodies were found not to be entirely equivalent in functional assays. One antibody, M P T 3 1 - B G 4 , was less effective at inhibiting T cell rosettes (64.3 +- 11.3% in 7 experiments) than the three other anti-CD2 antibodies or O K T l l (99.4 -+ 1.7% in 8 experiments). When tested for the ability to inhibit T cell proliferative responses to an optimal concentration of P H A , M P T 3 1 - B G 4 was more inhibitory (35.5 -+ 3.6% in 6 experiments) than the other antibodies ( 0 . 2 - 1 8 . 8 % inhibition). Each antibody inhibited P W M responses of T cells, but M P T 3 1 - B G 4 was the most inhibitory (79.8 -+ 1.4% vs. 2 8 . 6 - 5 2 . 8 % ) . In contrast, the ability o f M P T 3 1 - B G 4 to inhibit tetanus toxoid responses (34.2 -+ 10.7%) was less than that observed with the other anti-CD2 antibodies ( 4 8 . 3 - 7 4 . 5 % inhibition). It was shown, using cloned alloreactive T cell lines, that individual T cells have different degrees of sensitivity to inhibition by the M P T 3 1 - B G 4 antibody. O f 12 clones tested, five were strongly inhibited by M P T 3 1 - B G 4 ( 4 0 . 0 - 5 9 . 8 % inhibition), while seven were much less affected ( 0 - 2 1 % ) . These results suggest that different T cell clonotypes may be more or less dependent on additional interaction molecules such as CD2. Whether this correlates with specificity or functional attributes of the individual T cell is being investigated. The differential functional activity of the various anti-CD2 antibodies might be related either to avidity of the interactions or possibly to a relationship to a functional epitope(s) of the CD2 molecule.