CD8 dim but not CD8 bright cells positive to CD56 dominantly express KIR and are cytotoxic during visceral leishmaniasis

• Published in: Human immunology 2018-08, Vol.79 (8), p.616-620
• Main Authors: Kumari, Sarita, Shivam, Pushkar, Hansa, Jagadish, Jamal, Fauzia, Singh, Manish Kumar, Bimal, Sanjiva, Narayan, Shyam, Pandey, Krishna, Das, Vidya Nand Ravi, Das, Pradeep, Singh, Shubhankar K
• Format: Article
• Language: English
• ISSN: 0198-8859; 1879-1166
• DOI: 10.1016/j.humimm.2018.05.004

This study reports a structural and functional heterogeneity of CD8 CD56 NKT cells, which usually decrease quantitatively during visceral leishmaniasis. Based on fluorescence intensity of CD8 receptors on CD56 NKT cells, two populations of CD8 CD56 NKT cells have been identified. These cells were recognized as CD8 CD56 NKT and CD8 CD56 NKT cells. We further analyzed the functional nature of CD8 and CD8 positive CD56 NKT cells. In comparison to CD8 CD56 NKT cells, a significantly higher percentage of CD8 CD56 NKT cells expressed KIR during VL. The percentage of CD8 CD56 NKT cells expressing KIR was found 4 fold higher in VL as compared to healthy subjects. But, the difference was insignificant in case of CD8 CD56 NKT cells. CD8 CD56 NKT cells release granzyme B to kill the infected cells. A categorical difference was also observed in the function of CD8 CD56 NKT and CD8 CD56 NKT cells during visceral leishmaniasis. The percentage of granzyme B expressing CD8 CD56 NKT cells was 2.83 fold higher in VL compared to healthy subjects. But, there was no significant difference in granzyme B expressing CD8 CD56 NKT cells in samples from healthy and VL subjects. However, within VL subject, the percentage of granzyme B expressing CD8 CD56 NKT cells was 5.7 fold higher in comparison to CD8 CD56 NKT cells. This study concludes that CD8 CD56 NKT cells are more cytotoxic than CD8 CD56 NKT cells during VL.