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Altered proliferative response by T lymphocytes of Ly-6A (Sca-1) mice.

Stanford WL, Haque S, Alexander R, Liu X, Latour AM, Snodgrass HR, Koller BH, Flood PM - J. Exp. Med. (1997)

Bottom Line: To better understand the function of Ly-6A, we used gene targeting to produce Ly-6A mice which are healthy and have normal numbers and percentages of hematopoietic lineages.This enhanced proliferation is not due to alterations in kinetics of response, sensitivity to stimulant concentration, or cytokine production by the T cell population, and is manifest in both in vivo and in vitro T cell responses.Moreover, T cells from Ly-6A-deficient animals exhibit a prolonged proliferative response to antigen stimulation, thereby suggesting that Ly-6A acts to downmodulate lymphocyte responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7455, USA.

ABSTRACT
Ly-6A is a murine antigen which is implicated in lymphocyte activation and may be involved in activation of hematopoietic stem cells. Antibody cross-linking studies and antisense experiments have suggested that Ly-6A is a lymphocyte coactivation molecule. To better understand the function of Ly-6A, we used gene targeting to produce Ly-6A mice which are healthy and have normal numbers and percentages of hematopoietic lineages. However, T lymphocytes from Ly-6A-deficient animals proliferate at a significantly higher rate in response to antigens and mitogens than wild-type littermates. In addition, Ly-6A mutant splenocytes generate more cytotoxic T lymphocytes compared to wild-type splenocytes when cocultured with alloantigen. This enhanced proliferation is not due to alterations in kinetics of response, sensitivity to stimulant concentration, or cytokine production by the T cell population, and is manifest in both in vivo and in vitro T cell responses. Moreover, T cells from Ly-6A-deficient animals exhibit a prolonged proliferative response to antigen stimulation, thereby suggesting that Ly-6A acts to downmodulate lymphocyte responses.

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In vivo antigen responses are altered in Ly-6A−/− mice. Ly-6A−/− (black columns) and wild-type (striped columns) littermates were  primed with KLH antigen at days 0, 10, and 20. Mice were bled at day 20  for analysis of serum anti-KLH antibodies levels (B) and killed at day 24 to  measure proliferative responses by draining lymph node cells (A). (A) Ly-6A−/− draining lymph node cells proliferate at significantly higher levels  to Con A and various concentrations of KLH than wild-type littermates  (P <0.01 and P <0.03, respectively) but show no significant differences  in LPS response (P <0.11). (B) Serum concentration of anti-KLH antibodies is lower in Ly-6A−/− mice compared to wild-type littermates  measured by absorption of antibodies to ELISA plates coated with various  concentrations of KLH antigen (P <0.03).
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Figure 7: In vivo antigen responses are altered in Ly-6A−/− mice. Ly-6A−/− (black columns) and wild-type (striped columns) littermates were primed with KLH antigen at days 0, 10, and 20. Mice were bled at day 20 for analysis of serum anti-KLH antibodies levels (B) and killed at day 24 to measure proliferative responses by draining lymph node cells (A). (A) Ly-6A−/− draining lymph node cells proliferate at significantly higher levels to Con A and various concentrations of KLH than wild-type littermates (P <0.01 and P <0.03, respectively) but show no significant differences in LPS response (P <0.11). (B) Serum concentration of anti-KLH antibodies is lower in Ly-6A−/− mice compared to wild-type littermates measured by absorption of antibodies to ELISA plates coated with various concentrations of KLH antigen (P <0.03).

Mentions: Ly-6A and wild-type littermates were challenged with KLH by three footpad injections of 0.1 mg KLH in Freund's adjuvant, and draining lymph nodes were harvested 4 d after the tertiary immunization. Lymph node cells were then activated in culture in the presence of LPS, ConA, or KLH, and their proliferation rate measured by [3H]TdR incorporation. Ly-6A cells proliferated at significantly higher rates to KLH and ConA than wild-type lymphocytes (Fig. 7 A). In fact, incorporation of [3H]TdR by Ly-6A−/− cells was 150% higher at 1 μg/ml KLH (P <0.03), 168% higher at 5 μg/ml KLH (P <0.02), 191% higher at 10 μg/ml KLH (P <0.01), and 302% higher at 1 μg/ml ConA (P <0.01). Lymph node cells isolated from animals immunized with Freund's adjuvant alone did not respond to KLH antigen in vitro (data not shown). In contrast, LPS activation of cells did not demonstrate any significant differences (P <0.11) in B cell proliferation between KLH immunized Ly-6A and wild-type littermates (Fig. 7 A). However, the anti-KLH antibody response was significantly lower in Ly-6A animals in comparison to wild-type animals (Fig. 7 B). Fig. 7 B summarizes the results from ELISA analysis of serum from 10 d post-secondary immunized littermates (four in each group) against four dilutions of KLH antigen. At all dilutions of KLH antigen, the ELISA absorbance was lower by the serum of the Ly-6A mice than the wild-type littermates (ranging from 38 to 99% lower; P <0.03).


Altered proliferative response by T lymphocytes of Ly-6A (Sca-1) mice.

Stanford WL, Haque S, Alexander R, Liu X, Latour AM, Snodgrass HR, Koller BH, Flood PM - J. Exp. Med. (1997)

In vivo antigen responses are altered in Ly-6A−/− mice. Ly-6A−/− (black columns) and wild-type (striped columns) littermates were  primed with KLH antigen at days 0, 10, and 20. Mice were bled at day 20  for analysis of serum anti-KLH antibodies levels (B) and killed at day 24 to  measure proliferative responses by draining lymph node cells (A). (A) Ly-6A−/− draining lymph node cells proliferate at significantly higher levels  to Con A and various concentrations of KLH than wild-type littermates  (P <0.01 and P <0.03, respectively) but show no significant differences  in LPS response (P <0.11). (B) Serum concentration of anti-KLH antibodies is lower in Ly-6A−/− mice compared to wild-type littermates  measured by absorption of antibodies to ELISA plates coated with various  concentrations of KLH antigen (P <0.03).
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Figure 7: In vivo antigen responses are altered in Ly-6A−/− mice. Ly-6A−/− (black columns) and wild-type (striped columns) littermates were primed with KLH antigen at days 0, 10, and 20. Mice were bled at day 20 for analysis of serum anti-KLH antibodies levels (B) and killed at day 24 to measure proliferative responses by draining lymph node cells (A). (A) Ly-6A−/− draining lymph node cells proliferate at significantly higher levels to Con A and various concentrations of KLH than wild-type littermates (P <0.01 and P <0.03, respectively) but show no significant differences in LPS response (P <0.11). (B) Serum concentration of anti-KLH antibodies is lower in Ly-6A−/− mice compared to wild-type littermates measured by absorption of antibodies to ELISA plates coated with various concentrations of KLH antigen (P <0.03).
Mentions: Ly-6A and wild-type littermates were challenged with KLH by three footpad injections of 0.1 mg KLH in Freund's adjuvant, and draining lymph nodes were harvested 4 d after the tertiary immunization. Lymph node cells were then activated in culture in the presence of LPS, ConA, or KLH, and their proliferation rate measured by [3H]TdR incorporation. Ly-6A cells proliferated at significantly higher rates to KLH and ConA than wild-type lymphocytes (Fig. 7 A). In fact, incorporation of [3H]TdR by Ly-6A−/− cells was 150% higher at 1 μg/ml KLH (P <0.03), 168% higher at 5 μg/ml KLH (P <0.02), 191% higher at 10 μg/ml KLH (P <0.01), and 302% higher at 1 μg/ml ConA (P <0.01). Lymph node cells isolated from animals immunized with Freund's adjuvant alone did not respond to KLH antigen in vitro (data not shown). In contrast, LPS activation of cells did not demonstrate any significant differences (P <0.11) in B cell proliferation between KLH immunized Ly-6A and wild-type littermates (Fig. 7 A). However, the anti-KLH antibody response was significantly lower in Ly-6A animals in comparison to wild-type animals (Fig. 7 B). Fig. 7 B summarizes the results from ELISA analysis of serum from 10 d post-secondary immunized littermates (four in each group) against four dilutions of KLH antigen. At all dilutions of KLH antigen, the ELISA absorbance was lower by the serum of the Ly-6A mice than the wild-type littermates (ranging from 38 to 99% lower; P <0.03).

Bottom Line: To better understand the function of Ly-6A, we used gene targeting to produce Ly-6A mice which are healthy and have normal numbers and percentages of hematopoietic lineages.This enhanced proliferation is not due to alterations in kinetics of response, sensitivity to stimulant concentration, or cytokine production by the T cell population, and is manifest in both in vivo and in vitro T cell responses.Moreover, T cells from Ly-6A-deficient animals exhibit a prolonged proliferative response to antigen stimulation, thereby suggesting that Ly-6A acts to downmodulate lymphocyte responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7455, USA.

ABSTRACT
Ly-6A is a murine antigen which is implicated in lymphocyte activation and may be involved in activation of hematopoietic stem cells. Antibody cross-linking studies and antisense experiments have suggested that Ly-6A is a lymphocyte coactivation molecule. To better understand the function of Ly-6A, we used gene targeting to produce Ly-6A mice which are healthy and have normal numbers and percentages of hematopoietic lineages. However, T lymphocytes from Ly-6A-deficient animals proliferate at a significantly higher rate in response to antigens and mitogens than wild-type littermates. In addition, Ly-6A mutant splenocytes generate more cytotoxic T lymphocytes compared to wild-type splenocytes when cocultured with alloantigen. This enhanced proliferation is not due to alterations in kinetics of response, sensitivity to stimulant concentration, or cytokine production by the T cell population, and is manifest in both in vivo and in vitro T cell responses. Moreover, T cells from Ly-6A-deficient animals exhibit a prolonged proliferative response to antigen stimulation, thereby suggesting that Ly-6A acts to downmodulate lymphocyte responses.

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