Interleukin 4 stimulates infection and temporary growth of human neonatal lymphocytes exposed in vitro to human T-lymphotropic virus type I, but fails to substitute for interleukin 2 in the immortalization of infected cultures.
It has been shown that interleukin 4 (IL-4) stimulates the proliferation of cells from patients affected by adult T-cell leukaemia, the haematological malignancy aetiologically associated with human T-lymphotropic virus type I (HTLV-I). In the present study, human neonatal lymphocytes were exposed to HTLV-I in vitro in the presence of IL-4. The results showed that: (i) cultures exposed to HTLV-I in the presence of either IL-4 or IL-2 bound IL-4; (ii) IL-4 did not substitute for IL-2 as a growth factor in cell lines previously infected and maintained in IL-2; (iii) cultures exposed to HTLV-I and maintained in IL-4 or IL-2 became infected; and (iv) IL-4 sustained the growth of HTLV-I-infected cultures for a maximum of 14 weeks. Moreover, HTLV-I-infected cultures grown in IL-4 showed upregulation of the IL-4 message and lower expression of HLA-DR and CD25 when compared with counterpart cultures maintained in IL-2. These results suggest that continuous growth of T-lymphocytes induced in vitro by HTLV-I infection, at least temporarily, requires signals specifically provided by IL-2 and not by IL-4.
Mastino
A
A
Institute of Microbiology, Faculty of Science, University of Messina, Italy.
Grelli
S
S
Favalli
C
C
Matteucci
C
C
De Carli
M
M
Garaci
E
E
Macchi
B
B
D002455:Cell Division; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D015490:HTLV-I Infections / Q000473:pathology / Q000821:virology*; D015368:Human T-lymphotropic virus 1; D006801:Humans; D016130:Immunophenotyping; D007231:Infant, Newborn; D007376:Interleukin-2 / Q000378:metabolism / Q000494:pharmacology; D015847:Interleukin-4 / Q000378:metabolism / Q000494:pharmacology*; D019948:Receptors, Interleukin-4 / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology*
D007376:Interleukin-2; D019948:Receptors, Interleukin-4; D015847:Interleukin-4