The HML-1 antigen of intestinal lymphocytes is an activation antigen.
The Ag recognized by the mAb HML-1 is expressed on more than 90% of human intestinal intraepithelial lymphocytes, whereas in other lymphoid tissues it is rarely or not expressed. In the present study, we have investigated the percentage of HML-1-positive cells in the human intestinal lamina propria and the coexpression of HML-1 with different T cell subset markers. In addition, we studied the inducibility of HML-1 on PBL which normally are HML-1-negative. Flow cytometric analysis of isolated intestinal lamina propria lymphocytes (LPL) showed that about 40% of the cells expressed HML-1, the majority belonging to the CD8-positive subpopulation. Virtually all LPL expressed CD45RO, whereas the percentage of CD29-positive cells was only about 50%, similar to PBL. There were only few cells expressing CD45RA or Leu-8 in the lamina propria. HML-1-positive cells were almost exclusively CD45RA-negative, but were found in both the CD29-positive and the CD29-negative subpopulation of LPL. In vitro stimulation of PBL showed that the expression of HML-1 was inducible on T cells by mitogens, phorbolester, Ag, and rIL-2. Expression of HML-1 was induced with a different time course and with differences in the response to the investigated stimuli compared with CD25. Activated HML-1-positive PBL were also predominantly CD45RA-negative. The findings show that HML-1 is an Ag, which is expressed in vivo on a specific subset of previously activated T cells in the unique environment of the intestinal mucosa, and which can be induced in vitro by different activation signals on PBL.
Schieferdecker
H L
HL
Department of Medicine, Free University of Berlin, Federal Republic of Germany.
Ullrich
R
R
Weiss-Breckwoldt
A N
AN
Schwarting
R
R
Stein
H
H
Riecken
E O
EO
Zeitz
M
M
D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000032:analysis*; D018951:Antigens, CD20; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D017252:CD3 Complex; D016827:CD8 Antigens; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007422:Intestines / Q000166:cytology / Q000276:immunology*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D015375:Receptors, Interleukin-2 / Q000032:analysis
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018951:Antigens, CD20; D000944:Antigens, Differentiation, B-Lymphocyte; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D016827:CD8 Antigens; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2