https://www.researchgate.net/post/How_to_improve_the_yield_of_RNA_from_neutrophils

https://www.researchgate.net/post/How_can_I_isolate_RNA_from_human_neutrophil

https://www.researchgate.net/post/Sharing-neutrophil-isolation-and-RNA-extraction-protocol-work-flow

You may want to try RNAzol; it is similar to Trizol but specifically designed for RNA extraction. It works on a variety of sample inputs and has high recovery, so you can successfully extract RNA's with low copy number. For low-concentration RNA's, you can add carrier to help precipitate the RNA.

Alternatively. you can try the Qiagen RNeasy kits. They are very popular and simple to use, however they do not provide the same level of yield. This type of column kit relies on different chemistry, which may or may not be more suitable for your samples.

RNA extraction from sperm-challenged PMNs and control groups

The PMN cells exhibiting NETosis were collected and re-suspended in 100µl of PBS in 1.5 ml MCTs. The cells were mixed with 900 µl of Trizol reagent (Invitrogen) as per manufacturer’s instructions. The RNA pellet was dried in the air followed by dissolved in 30 µl of DEPC treated water and placed in a heating block at 55ºC for 5 min. Extracted RNA was quantified using a NanoDrop ND-1000 UV–Vis Spectrophotometer (NanoDrop Technologies Inc., Wilmington, DE, USA). The quality and integrity of extracted RNA were assessed by running 200ng of RNA (heated at 65°C for 1 minute) in non-denaturing TAE buffered 1.2% agarose.

Reference: Article A Higher Abundance of O-Linked Glycans Confers a Selective A...