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.
Department of Medicine, Free University of Berlin, Federal Republic of Germany.
H L
HL
Schieferdecker
R
R
Ullrich
A N
AN
Weiss-Breckwoldt
R
R
Schwarting
H
H
Stein
E O
EO
Riecken
M
M
Zeitz
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