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Active immunization with human interleukin-15 induces neutralizing antibodies in non-human primates

View Article: PubMed Central - PubMed

ABSTRACT

Background: Interleukin-15 is an immunostimulatory cytokine overexpressed in several autoimmune and inflammatory diseases such as Rheumatoid Arthritis, psoriasis and ulcerative colitis; thus, inhibition of IL-15-induced signaling could be clinically beneficial in these disorders. Our approach to neutralize IL-15 consisted in active immunization with structurally modified human IL-15 (mhIL-15) with the aim to induce neutralizing antibodies against native IL-15. In the present study, we characterized the antibody response in Macaca fascicularis, non-human primates that were immunized with a vaccine candidate containing mhIL-15 in Aluminum hydroxide (Alum), Montanide and Incomplete Freund’s Adjuvant.

Results: Immunization with mhIL-15 elicited a specific antibodies response that neutralized native IL-15-dependent biologic activity in a CTLL-2 cell proliferation assay. The highest neutralizing response was obtained in macaques immunized with mhIL-15 adjuvanted in Alum. This response, which was shown to be transient, also inhibited the activity of simian IL-15 and did not affect the human IL-2-induced proliferation of CTLL-2 cells. Also, in a pool of synovial fluid cells from two Rheumatoid Arthritis patients, the immune sera slightly inhibited TNF-α secretion. Finally, it was observed that this vaccine candidate neither affect animal behavior, clinical status, blood biochemistry nor the percentage of IL-15-dependent cell populations, specifically CD56+ NK and CD8+ T cells.

Conclusion: Our results indicate that vaccination with mhIL-15 induced neutralizing antibodies to native IL-15 in non-human primates. Based on this fact, we propose that this vaccine candidate could be potentially beneficial for treatment of diseases where IL-15 overexpression is associated with their pathogenesis.

No MeSH data available.


Related in: MedlinePlus

Abs response in macaques immunized with mhIL-15 corresponding to 15 days after the third immunization. a ELISA for Abs titers against IL-15. The plate was coated with 1 μg/ml mhIL-15 and the serum from each animal was evaluated in twofold serial dilutions (starting dilution 1:1000). All animals developed an Abs response, except pre-immune and placebo macaques. The line represents the mean values of Abs titers calculated from duplicate samples of individual monkeys (n = 3) corresponding to each experimental group. b ELISA for recognition of native IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml native human IL-15 and the pool of sera from each group was evaluated in fixed dilution, 1:4000. c Serum neutralization titers of macaques calculated from the data obtained in the CTLL-2 cell proliferation assay. The line represents the mean values of neutralization titers (expressed as 1/ID50) calculated from duplicate samples of individual animals (n = 3). The ID50 was determined by inhibiting of human IL-15-induced proliferation of CTLL-2 cells
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Fig3: Abs response in macaques immunized with mhIL-15 corresponding to 15 days after the third immunization. a ELISA for Abs titers against IL-15. The plate was coated with 1 μg/ml mhIL-15 and the serum from each animal was evaluated in twofold serial dilutions (starting dilution 1:1000). All animals developed an Abs response, except pre-immune and placebo macaques. The line represents the mean values of Abs titers calculated from duplicate samples of individual monkeys (n = 3) corresponding to each experimental group. b ELISA for recognition of native IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml native human IL-15 and the pool of sera from each group was evaluated in fixed dilution, 1:4000. c Serum neutralization titers of macaques calculated from the data obtained in the CTLL-2 cell proliferation assay. The line represents the mean values of neutralization titers (expressed as 1/ID50) calculated from duplicate samples of individual animals (n = 3). The ID50 was determined by inhibiting of human IL-15-induced proliferation of CTLL-2 cells

Mentions: Figure 3a depicts the anti-IL-15 Abs titers detected by ELISA in serum from macaques immunized with mhIL-15 in Alum, Montanide or IFA after the third immunization. Average titer was higher than 1:20000 in all groups, except in the pre-immune and placebo monkeys. The highest response was obtained in the group immunized with IFA eliciting an average titer of 1:28351; while in the Alum and Montanide groups the calculated average titer was 1:24660 and 1:24616, respectively.Fig. 3


Active immunization with human interleukin-15 induces neutralizing antibodies in non-human primates
Abs response in macaques immunized with mhIL-15 corresponding to 15 days after the third immunization. a ELISA for Abs titers against IL-15. The plate was coated with 1 μg/ml mhIL-15 and the serum from each animal was evaluated in twofold serial dilutions (starting dilution 1:1000). All animals developed an Abs response, except pre-immune and placebo macaques. The line represents the mean values of Abs titers calculated from duplicate samples of individual monkeys (n = 3) corresponding to each experimental group. b ELISA for recognition of native IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml native human IL-15 and the pool of sera from each group was evaluated in fixed dilution, 1:4000. c Serum neutralization titers of macaques calculated from the data obtained in the CTLL-2 cell proliferation assay. The line represents the mean values of neutralization titers (expressed as 1/ID50) calculated from duplicate samples of individual animals (n = 3). The ID50 was determined by inhibiting of human IL-15-induced proliferation of CTLL-2 cells
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036325&req=5

Fig3: Abs response in macaques immunized with mhIL-15 corresponding to 15 days after the third immunization. a ELISA for Abs titers against IL-15. The plate was coated with 1 μg/ml mhIL-15 and the serum from each animal was evaluated in twofold serial dilutions (starting dilution 1:1000). All animals developed an Abs response, except pre-immune and placebo macaques. The line represents the mean values of Abs titers calculated from duplicate samples of individual monkeys (n = 3) corresponding to each experimental group. b ELISA for recognition of native IL-15 by Abs from sera of immunized macaques. The plate was coated with 1 μg/ml native human IL-15 and the pool of sera from each group was evaluated in fixed dilution, 1:4000. c Serum neutralization titers of macaques calculated from the data obtained in the CTLL-2 cell proliferation assay. The line represents the mean values of neutralization titers (expressed as 1/ID50) calculated from duplicate samples of individual animals (n = 3). The ID50 was determined by inhibiting of human IL-15-induced proliferation of CTLL-2 cells
Mentions: Figure 3a depicts the anti-IL-15 Abs titers detected by ELISA in serum from macaques immunized with mhIL-15 in Alum, Montanide or IFA after the third immunization. Average titer was higher than 1:20000 in all groups, except in the pre-immune and placebo monkeys. The highest response was obtained in the group immunized with IFA eliciting an average titer of 1:28351; while in the Alum and Montanide groups the calculated average titer was 1:24660 and 1:24616, respectively.Fig. 3

View Article: PubMed Central - PubMed

ABSTRACT

Background: Interleukin-15 is an immunostimulatory cytokine overexpressed in several autoimmune and inflammatory diseases such as Rheumatoid Arthritis, psoriasis and ulcerative colitis; thus, inhibition of IL-15-induced signaling could be clinically beneficial in these disorders. Our approach to neutralize IL-15 consisted in active immunization with structurally modified human IL-15 (mhIL-15) with the aim to induce neutralizing antibodies against native IL-15. In the present study, we characterized the antibody response in Macaca fascicularis, non-human primates that were immunized with a vaccine candidate containing mhIL-15 in Aluminum hydroxide (Alum), Montanide and Incomplete Freund’s Adjuvant.

Results: Immunization with mhIL-15 elicited a specific antibodies response that neutralized native IL-15-dependent biologic activity in a CTLL-2 cell proliferation assay. The highest neutralizing response was obtained in macaques immunized with mhIL-15 adjuvanted in Alum. This response, which was shown to be transient, also inhibited the activity of simian IL-15 and did not affect the human IL-2-induced proliferation of CTLL-2 cells. Also, in a pool of synovial fluid cells from two Rheumatoid Arthritis patients, the immune sera slightly inhibited TNF-α secretion. Finally, it was observed that this vaccine candidate neither affect animal behavior, clinical status, blood biochemistry nor the percentage of IL-15-dependent cell populations, specifically CD56+ NK and CD8+ T cells.

Conclusion: Our results indicate that vaccination with mhIL-15 induced neutralizing antibodies to native IL-15 in non-human primates. Based on this fact, we propose that this vaccine candidate could be potentially beneficial for treatment of diseases where IL-15 overexpression is associated with their pathogenesis.

No MeSH data available.


Related in: MedlinePlus