Induction of T cell aggregation by antibody to a 16kd human leukocyte surface antigen

• Published in: The Journal of immunology (1950) Vol. 133; no. 5; pp. 2496 - 2501
• Main Authors: Chen, YX, Welte, K, Gebhard, DH, Evans, RL
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.11.1984
• Subjects: Animals; antibodies; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - physiology; Antigens, Surface - immunology; Antigens, Surface - isolation & purification; Binding Sites, Antibody; Binding, Competitive; Cell Aggregation; cell surface; Humans; Leu-13 antigen; leukocytes; Leukocytes - classification; Leukocytes - immunology; Leukocytes - metabolism; Lymphocyte Activation; lymphocytes T; man; Mice; Mice, Inbred BALB C; Molecular Weight; Precipitin Tests; Sezary Syndrome - immunology; T-Lymphocytes - immunology; T-Lymphocytes - physiology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.133.5.2496

We describe studies of a human leukocyte antigen, termed Leu-13, that is defined by a mouse monoclonal antibody that reacts with T and B lymphocytes. Optimal staining of T cells requires a much higher concentration of alpha Leu-13 (greater than or equal to 200 micrograms/ml) than alpha Leu-4 (6 micrograms/ml). However, the fluorescence intensity of T cells labeled with alpha Leu-13, washed and kept at 4 degrees C for different periods, does not diminish more rapidly than the fluorescence of T cells stained with alpha Leu-4 and treated the same way. These results indicate that the novel binding pattern of alpha Leu-13 is not due to weak affinity. Immunoprecipitation and SDS-PAGE analysis indicates that alpha Leu-13 precipitates a major 16-kilodalton (16kd) band and a minor 26kd component from Nonidet P-40-solubilized membrane of normal T cells that are surface-labeled with 125I. The similar sizes of the 16kd to 26kd (Leu-13) and 22kd to 28kd (Leu-4) molecules prompted us to compare the capacity of alpha Leu-13 and alpha Leu-4 to trigger T cell functions, and to co-modulate and co-precipitate the T cell antigen receptor. Unlike alpha Leu-4, alpha Leu-13 does not trigger T cell proliferation or augment NK activity, but inhibits the mitogenic effect of alpha Leu-4/T3 antibodies. alpha Leu-13 also induces T cells to clump into large aggregates after 16 hr of culture at 37 degrees C, but not at 4 degrees C. T cell aggregation is triggered by concentrations of alpha Leu-13 as low as 12.5 ng/ml. At this concentration, alpha Leu-13 is not detectable on the surface of T cells by indirect immunofluorescence analysis in a FACS. On leukemic T cells, alpha Leu-4 was found to co-modulate and co-precipitate a 38kd to 44kd dimer having apparent idiotypic determinants, whereas alpha Leu-13 did not. The possible significance of these findings to immune regulation by T cells is discussed.