Editing 2749: Lymphocytes

{{comic
| number    = 2749
| date      = March 13, 2023
| title     = Lymphocytes
| image     = lymphocytes_2x.png
| imagesize = 651x733px
| noexpand  = true
| titletext = It's very hard to detect, but recent studies have determined that when plasma B cells are producing antibodies, they go 'pew pew pew'
}}

==Explanation==
The human body contains many different types of immune cells. This comic is a list of {{w|lymphocyte}}s, a specific type of immune cell that is found in blood and lymph. As the comic goes on, in the style of many "informative" xkcd comics, the descriptions of the names of the cells get more and more removed from reality. Though many of the cells are real, only two descriptions are accurate, those for the plasma B cell and that of the out of context D cell. The diagrams are either uninformingly similar to each other, as an extremely generic diagram of a biological cell, or made to look somewhat like the item spoofed by the description.

The title text is possibly a reference to this recent study: https://pubs.acs.org/doi/10.1021/acsnano.3c00638

{| class="wikitable"
! Name !! Real Lymphocyte? !! Randall's description !! Comment
|-
| {{w|Plasma B cell}}s || Yes || Churn out antibodies || Does as the comic says.
No parody, except for the very vague diagram of a cell with a perinuclear region within it that could also just be a fried egg.
|-
| Naïve B cells || Yes || Try to stop pathogens by asking nicely || {{w|B cell}}s that have not yet been exposed to an antigen. Can only "ask nicely" for pathogens to stop because they cannot yet contribute to the immune system.
Image remains as much just a 'fried egg' as the prior image.
|-
| {{w|Memory B cell}}s || Yes || Very quietly sing {{w|Memory_(Cats_song)|"Memory" from ''Cats''}} at all times || Long-lived B cells that "remember" an antigen they have previously encountered, allowing them to quickly respond to a reappearance of the same antigen.
"Memory" is one of the most famous songs from the 1981 Andrew Lloyd Webber ''{{w|Cats (musical)|Cats}}'' musical, and the otherwise very similar diagram appears to be singing notes.
|-
| {{w|Regulatory B cell}}s || Yes || Required by local ordinance || Suppress certain immune responses, or in other words, regulates the immune response, which is their actual namesake, as opposed to the made-up namesake of only being in the body because some regulation requires it.
Cells do follow instructions from DNA, and their environment, which might be considered to be local ordinances. The image is again just another ''slightly'' different version of the generic cell image.
|-
| CD8+ T cells || Yes || Melee combat || {{w|Cytotoxic T cell}}, responsible for killing cells which are cancerous or infected. Named after the surface protein "CD8" ("Cluster of Differentiation") it uses when searching for targets.
Possibly a reference to the tabletop gaming terminology where "d8" means 8-sided dice, "d4" means 4-sided dice, etc. D&D and many of its derivatives use d8s primarily for damage, particularly for some of the most common weapons like rapiers, longswords, and longbows, and also for several spells like Chill Touch or Ray of Frost. The image is again fairly generic without any gross distinction to it.
|-
| CD4+ T cells || Yes || Scream at other cells || {{w|T helper cell}}, releasing cytokines as a signal that prompts the immune system into action, thus "screaming" at other cells. Named after the surface protein "CD4" (see above), that is used for binding to other cells while "screaming".
The generic cell image seems to be shouting "AAAAAAAAA!". Possibly also a reference to the D&D spell "Vicious Mockery" which may involve screaming and does damage based on a "d4" die.
|-
| {{w|Gamma delta T cell|Gamma-Delta T cell}}s || Yes || Unknown / classified || T cells found largely in mucous membranes of the gut, with different T-cell receptors than normal. Effectively the immune system's first line of defense.
The image, this time, has a dashed outer line and a question-mark instead of any nucleus. ''{{w|Delta Force|Delta Force}}'' is a famous military special forces organization involved in classified and not-generally-known operations, and its operatives are unlikely to be identified in publically available images.
|-
| CDRW+ T cells || No || Rewritable, 700MB || Here, the meaning of "CD" is switched from {{w|Cluster of Differentiation}} to {{w|Compact Disc}}, as in the {{w|CD-RW}} re-writable media format. 700 megabytes is a common size format for CDs.
By skewing the 'cell' diagram into an oval, with concentric central 'nucleus' and adding some subtle radial and concentric lines, it now resembles a typical item of optical media.
|-
| DVD+R T cells || No || Different from DVD-R, though no one is sure how || {{w|DVD+R}} is a DVD format designed by {{w|HP Labs}}, while DVD-R (pronounced "dash R") came originally from {{w|Pioneer Corporation}} and was the earlier accepted system. The two formats are not trivially compatible, but many (re)writing DVD drives were made multiformat to automatically handle both of these, {{w|DVD-RAM}}, read/write versions and CD-density media, as necessary,  under the general label of "DVD±RW". The user then ends up not usually needing, or bothering, to know the technical differences.
Another 'skewed oval', with a few more lines (to perhaps suggest greater data density) but not functionally different from the prior diagram.
|-
| {{w|Natural killer cell}}s || Yes || Named by the world's coolest immunologist || Kills cells infected by intracellular pathogens and other malfunctioning (e.g. cancerous) cells, similar to CD8+ cells but part of the {{w|innate immune system}}. Randall likes the name of these cells more than the next item, making Rolf Kiessling and Hugh Pross "the world's coolest immunologist(s)."
The cell image is a bit more crinkled at the edge than any prior cell, but otherwise not remarkably distinctive.
|-
| ILC1, ILC2, and ILC3 cells || Yes || Named by a significantly less cool immunologist || {{w|Innate lymphoid cell}}s, regulating the innate immune system through signaling molecules. Named in [https://www.nature.com/articles/nri3365 this paper in Nature] by Hergen Spits, David Artis, Marco Colonna, Andreas Diefenbach, James P. Di Santo, Gerard Eberl, Shigeo Koyasu, Richard M. Locksley, Andrew N. J. McKenzie, Reina E. Mebius, Fiona Powrie and Eric Vivier, making them collectively much less cool than Kiessling and Pross above.
Represented by three small cell-images, snuggling close to each other without touching, and no real reason to assume which of the three is which.
|-
| D cells || No || Larger than C and AA cells, used in old flashlights || This is not a blood cell, but a {{w|D battery|"D cell" battery}}. Much like living organisms, the components of batteries are called {{w|Alkaline battery#Construction|"cells"}} (which forms the basis of Randall's pun) and they can be single-cell or {{w|Nine-volt battery#Technical specifications|multi-cell}}, though the two are often indistinguishable from each other to the casual user. Biological cells called "D cells" or {{w|delta cell}}s ''do'' actually exist, but they are not lymphocytes.

The battery in the comic is drawn as a diagrammatic 'cylinder', the cell edge forming a round-ended rectangle with a faint 'nearside' line to hint at its [[2509: Useful Geometry Formulas|3D nature]]. The 'nucleus' is pushed into one end of the shape, reminiscent of the distinctive 'cap' to {{w|Duracell|some batteries, commonly imitated}}, emphasizing the polarity of the item, but also represents a highly simplified version of how the electrolyte might be placed within the housing. 
|}

==Transcript==
:[Title] Lymphocytes
:[Subtitle] And their functions
:[A 4 by 3 grid of frames, each containing the name of the lymphocyte, a visual depiction of the cell and a description]

:[Row 1, Column 1]
:Plasma B cells
:[Egg-like shaped cell with the nucleus right from the middle]
:Churn out antibodies 

:[Row 1, Column 2]
:Naïve B cells
:[Almost circular cell with the nucleus in the middle]
:Try to stop pathogens by asking nicely 

:[Row 1, Column 3]
:Memory B cells
:[Like panel 2, but with some music notes next to it, as if it produces sound]
:Very quietly sing "memory" from Cats at all times 

:[Row 1, Column 4]
:Regulatory B cells
:[Like panel 2]
:Required by local ordinance 

:[Row 2, Column 1]
:CD8+ T cells
:[Also oblong, but with the nucleus left from the middle]
:Melee combat 

:[Row 2, Column 2]
:CD4+ T cells
:[Circular, with a large nucleus, saying ‘AAAAAAAAA!’]
:Scream at other cells 

:[Row 2, Column 3]
:Gamma-Delta T cells
:[Dashed circle with a question mark in the middle]
:Unknown / classified 

:[Row 2, Column 4]
:CDRW+ T cells
:[Shaped like a CD, with a large hole in the middle]
:Rewritable, 700MB 

:[Row 3, Column 1]
:DVD+R T cells
:[Shaped like a DVD, with a bit smaller hole in the middle]
:Different from DVD-R, though no one is sure how 

:[Row 3, Column 2]
:Natural killer cells
:[Irregularly shaped oblong cell with nucleus in the middle]
:Named by the world's coolest immunologist 

:[Row 3, Column 3]
:ILC1, ILC2, and ILC3 cells
:[Three cells]
:Named by a significantly less cool immunologist 

:[Row 3, Column 4]
:D cells
:[Cylindrical shaped ‘cell’, with a smaller cylindrical ‘nucleus’ inside it at the right, roughly shaped like a D battery]
:Larger than C and AA cells, used in old flashlights 


{{comic discussion}}

[[Category:Biology]]
[[Category:Science]]