Clinical sciences

Question 1

what is the p value and whats its sig value

Answer 1

Stat sig p value = 0.05 = probability that the null hypothesis is true/that you can reject the null hypothesis

Question 2

if a trial estimate is 1.4 what does that mean

Answer 2

Estimate 1.4 = 40% more likely to be in remission (or 1.4x)

Question 3

if a CI is described as (95% between 0.8 and 2) what does this mean

Answer 3

CI = estimate of precision (95% between 0.8 and 2) = 20% worsening of outcome and 100% improvement

Question 4

when do you use

• chi squared
• t test
• mann whitney u test

Answer 4

Chi squared: categorical data

T test: continuous variable that’s normally distributed (and in 2 groups)

Mann Whitney U test: continuous variable that’s NOT normally distributed (and is in 2 groups)

Question 5

case control study

• explain
• when do you use
• what bias?

Answer 5

for rare diseases. Start with the outcome. but get recall bias!

Question 6

cohort study
- what for
what is it
what bias

Answer 6

Cohort: for common diseases. Start with the exposure/risk. Get channeling bias (if haven’t randomised ppl to a tx, there’s often a reason they ended up with that one)

Question 7

type 1 error
- what is it
what causes it

Answer 7

Type 1: when we get a false positive
= incorrectly concluding that there’s a stat sig difference in a dataset
— (causes: failure to adjust for confounders, inadequate blinding, not performing an intention to treat analysis, poor randomisation)

Question 8

type 2 error

what is it and what causes it

Answer 8

Type 2: when we get a false negative
= incorrectly conclusing that there’s no stat sig difference in a dataset
— (sample size is too small; classically inadequately powered study)
Aka boy who cried wolf: 1st time he cried wolf, village came running and he had made it up = false positive
but 2nd time, there is a wolf but village doesn’t believe him = false negative

Question 9

sensitivity equation

Answer 9

= the number of pts with a positive test who have the disease divided by all pts with the disease
if high wont miss many ppl with the disease
= few false negatives aka good for ruling out diseases (like d-dimer in pe)
true positive = new test +ve & ref test +ve
Sensitive so it picks up lots of trash as +ve too
- False neg = new test -ve and ref test +ve

Question 10

specificity equation and what is it

Answer 10

Specificity = true neg / (true neg + false positive)
= the number of pts who have a negative test and dont have the disease dividedby the number of patients who dont have the disease
= few false positives; so if its positive you probably have the disease = relatively diagnostic
- the test is specific to the disease, only positive when you have it
- true neg = both neg
= False +ve = new test +ve and ref test -ve

Question 11

NNT equation & what is it

Answer 11

NNT = 1/absolute risk difference

• ARR = the event rate in the control arm - event rate in treatment arm
• aka 10% of control group relapsed vs 5% of treatment arm
• Absolute risk diff = 10-5 = 5% = 0.05
• so NNT = 1/0.05 = 20

Question 12

endothelin what is used in primary pulmonary hypertension

Answer 12

endothelin antagonist

Question 13

p53 is a what

Answer 13

tumour suppressor

Question 14

positive and negative predictive values

Answer 14

Negative predictive value = chance of testing negative and not having the disease = true negs/all the people who tested negative

PPV: true positives/all who tested positive

Question 15

complement deficiencies predispose to ?
- c1 inh protein def?
- C1q, C1rs, C2, C4 deficiency 
C3 deficiency
C5 deficiency: 
C5-9 deficiency:

Answer 15

• C5-9 def predisposes to n.meningitidis infections
  
  • C1q, C1rs, C2 and C4: immune complex disease (eg SLE, HSP)

NOTES
C1 inhibitor protein deficiency: hereditary angioedema

C1q, C1rs, C2, C4 deficiency (classical pathway components)

C3 deficiency: recurrent bacterial infections (esp encapsulated)

C5 deficiency: Leiner disease (recurrent diarrhoea, wasting and seborrhoeic dermatitis)

C5-9 deficiency:encodes the membrane attack complex (MAC)

Question 16

relative risk equation
A total of 100 patients received the new drug whilst 100 patients received a placebo. Of the patients taking the experimental drug, 60 felt improved symptoms compared to 20 patients in the control group.

whats the RR of the drug improving migraine syms

Answer 16

Relative risk = EER/CER = ratio of a risk happening in the experimental group vs control group

EG 60/100 in expt group had improved symptoms, 20/100 in placebo group did - so 60/20 = 3

Question 17

boy, brother & their male maternal cousin what is it most likely?

Answer 17

mitochondrial

Question 18

HLA
A3
B51
B27 (3)
DQ2
DQ8
DR2 (2)
DR3 (3)
DR4 (2)

Answer 18

HLA-A3: haemochromatosis
HLA-B51: Behcet’s disease

HLA-B27
• ankylosing spondylitis
• reactive arthritis
• acute anterior uveitis

HLA-DQ2/DQ8: coeliac disease

HLA-DR2
• narcolepsy
• Goodpasture’s

HLA-DR3
• dermatitis herpetiformis
• Sjogren’s syndrome
• primary biliary cirrhosis

HLA-DR4
• type 1 diabetes mellitus
rheumatoid arthritis - esp DRB1 gene (DRB104:01 and DRB104:04 hence the association with DR4)

Question 19

expressivity v penetrance

Answer 19

· Expressivity = extent to which a genotype shows its phenotypic expression in an individual
· Penetrance = proportion of a population of individuals who carry a disease-causing allele who express the related disease phenotype.

Question 20

turner’s

• denoted as?
• features
• most common cardiac abn

Answer 20

· 45X0
· Short, webbed neck, shield chest, primary amenorrhoea, high arched palate, horseshoe kidney, high gonadotrophins
· Most common cardiac defect: bicuspid aortic valve (also ass w aortic root dilatation & coarctation of aorta)

NOTES
Features
• short stature
• shield chest, widely spaced nipples
• webbed neck
• bicuspid aortic valve (15%), coarctation of the aorta (5-10%)
• primary amenorrhoea
• cystic hygroma (often diagnosed prenatally)
• high-arched palate
• short fourth metacarpal
• multiple pigmented naevi
• lymphoedema in neonates (especially feet)
• gonadotrophin levels will be elevated
• Hypothyroidism
• horseshoe kidney (most common renal abn)
• increased incidence of autoimmune disease (especially autoimmune thyroiditis) and Crohn’s disease

Question 21

fragile x
- inheritance
- type of disease
fts in males and females

Answer 21

Features in males
	• learning difficulties
	• large low set ears, long thin face, high arched palate
	• Macro-orchidism
	• hypotonia
	• autism is more common
	• mitral valve prolapse

Females (1 fragile chromosome and 1 normal): normal to mild

trinucleotide repeat

Question 22

standard error of the mean equation

Answer 22

SEM = standard deviation / square root (number of patients)

So the SEM gets smaller as the sample size increases

Question 23

breast feeding CI

• drugs
• other 2

Answer 23

Drugs to avoid:
	• abx: ciprofloxacin, tetracycline, chloramphenicol, sulphonamides
	• psych: lithium, benzodiazepines, clozapine 
	• aspirin
	• carbimazole
	• methotrexate
	• sulfonylureas
	• cytotoxic drugs
	• Amiodarone

Other CI
• Galactosaemia (babies can’t metabolise galactose - so can’t BF as it has lots of lactose in - they need non-lactose formula)
• viral infection

Question 24

X-linked recessive diseases (14)

Answer 24

• Androgen insensitivity syndrome 
	• Becker muscular dystrophy
	• Colour blindness
	• Duchenne muscular dystrophy
	• Fabry's disease
	• G6PD deficiency
	• Haemophilia A,B
	• Hunter's disease
	• Lesch-Nyhan syndrome
	• Nephrogenic diabetes insipidus
	• Ocular albinism
	• Retinitis pigmentosa
	• Wiskott-Aldrich syndrome
Chronic granulomatous disease: X-linked recessive in >70% (but some other patterns of inheritance)

Question 25

key feature of a normal distribution (and any others)

Answer 25

KEY BITS · Mean = mode = median · standard deviation (SD) is a measure of how much dispersion exists from the mean NOTES Properties of the Normal distribution • symmetrical i.e. Mean = mode = median • 68.3% of values lie within 1 SD of the mean • 95.4% of values lie within 2 SD of the mean • 99.7% of values lie within 3 SD of the mean • this is often reversed, so that within 1.96 SD of the mean lie 95% of the sample values the range of the mean - (1.96 *SD) to the mean + (1.96 * SD) is called the 95% confidence interval - Ie If a repeat sample of 100 observations are taken from the same group 95 of them would be expected to lie in that range Standard deviation - the standard deviation (SD) is a measure of how much dispersion exists from the mean - SD = square root (variance)

Question 26

equations - LV ejection fraction - stroke volume - CO - systemic vascular resistance - pulse pressure (2 factors that increase it)

Answer 26

· LV ejection fraction = (stroke volume / end diastolic LV volume) x100% NOTES Stroke volume = end diastolic LV volume - end systolic LV volume Cardiac output = stroke volume x heart rate Systemic vascular resistance = mean arterial pressure / cardiac output Pulse pressure = Systolic Pressure - Diastolic Pressure - Factors which increase pulse pressure ○ a less compliant aorta (this tends to occur with advancing age) increased stroke volume

Question 27

radial nerve - continuation of what? - damage at axilla > ? - whats missing if damaged later on? - sensory innervation of the hand - where? - main motor effect

Answer 27

= Continuation of posterior cord of the brachial plexus (root values C5 to T1) Patterns of damage: · wrist drop • sensory loss to small area between the dorsal aspect of the 1st and 2nd metacarpals Axillary damage = as above + paralysis of triceps Sensory to hand: back of hand from thumb > half way through ring finger (excl tips of index/middle/ring) + abit of the palmar aspect of the thumb Extension (forearm, wrist, fingers, thumb)

Question 28

what do you use these tests for - chi squared - t test - mann whitney u

Answer 28

• Chi squared: categorical data • T test: continuous variable that’s normally distributed (and in 2 groups) Mann Whitney U test: continuous variable that’s NOT normally distributed (and is in 2 groups)

Question 29

difference between type 1 and type 2 errors

Answer 29

• Type 1: when we get a false positive = incorrectly concluding that there’s a stat sig difference in a dataset ○ — (causes: failure to adjust for confounders, inadequate blinding, not performing an intention to treat analysis, poor randomisation) • Type 2: when we get a false negative = incorrectly conclusing that there’s no stat sig difference in a dataset ○ — (sample size is too small; classically inadequately powered study) Aka boy who cried wolf: 1st time he cried wolf, village came running and he had made it up = false positive • but 2nd time, there is a wolf but village doesn’t believe him = false negative

Question 30

whats the power of the study | how can you increase it

Answer 30

Power of the study = the probability of correctly rejecting the null hypothesis when it's false - The probability of detecting a stat sig difference - Power = 1 - probability of a type 2 error Power is increased with increased sample size

Question 31

``` damage to this causes? - ulnar nerve radial nerve long thoracic nerve axillary nerve ```

Answer 31

Ulnar nerve damage > claw hand Radial nerve damae > wrist drop Long thoracic nerve damage > winged scapula loss of shoulder abduction: deltoid muscle, axillary nerve (C5 + C6)

Question 32

damage to lower trunk of BP causes? damage to upper trunk?

Answer 32

Erb-Duchenne palsy ('waiter's tip') • damage of the upper trunk of the brachial plexus (C5,C6) • may be secondary to shoulder dystocia during birth • the arm hangs by the side and is internally rotated, elbow extended Klumpke injury • damage of the lower trunk of the brachial plexus (C8, T1) • may be secondary to shoulder dystocia during birth. Also may be caused by a sudden upward jerk of the hand associated with Horner's syndrome

Question 33

median nerve - from what - supplies what motor and what sensory in hand

Answer 33

``` (C6, C8, T1) LOAF muscles - Lateral two lumbricals - Opponens pollis - Abductor pollis brevis - Flexor pollis brevis ``` Features depend on the site of the lesion: • wrist: paralysis of thenar muscles, opponens pollicis • elbow: loss of pronation of forearm and weak wrist flexion Palmar aspect of lateral 3½ fingers

Question 34

ulnar nerve - from what of BP - motor stuff - sensory stuff

Answer 34

c8 t1 intrinsic hand muscles. exc LOAF wrist flexion medial 1.5 fingers

Question 35

PCR - what do you need - main adv? reverse transcriptase PCR: whats diff

Answer 35

thermostable DNA polymerase (taq), 2 DNA oligonucleotide primers. adv: very sensitive only need 1 strand of sample dna. rev trans PCR: to amplify RNA. RNA converted to DNA by rev transcriptase.

Question 36

leptin + ghrelin - where is each from what effects

Answer 36

Leptin: • Secreted by adipose tissue ○ More adipose if obese = higher levels • Stims release of MSH • Plays key role in regulation of body wt • High levels decrease appetite NOTES Leptin • acts on satiety centres in the hypothalamus and decreases appetite • stimulates the release of melanocyte-stimulating hormone (MSH) and corticotrophin-releasing hormone (CRH) • Low levels of leptin stimulates the release of neuropeptide Y (NPY) DETAILS Ghrelin • stimulates hunger • produced mainly by the P/D1 cells lining the fundus of the stomach and epsilon cells of the pancreas levels increase before meals and decrease after meals

Question 37

homocystinuria - inheritance - pathology - features - Ix? - Tx?

Answer 37

· AR · deficiency of cystathionine beta synthase >> very high plasma and urine homocysteine ``` Features • often: fine, fair hair • MSK ○ Marfanoid body habitus: arachnodactyly etc ○ osteoporosis ○ kyphosis • neuro: may have learning diffs, seizures • ocular ○ downwards (inferonasal) dislocation of lens ○ severe myopia • increased risk of arterial and VTE • malar flush, livedo reticularis ``` Investigations • high homocysteine levels in serum and urine • cyanide-nitroprusside test (also positive in cystinuria) Tx: vitamin B6 (pyridoxine)supplements.

Question 38

incidence v prevalence | relationship?

Answer 38

* incidence = number of new cases per population in a given time period * prevalence = total number of cases per population at a particular point in time. * prevalence = incidence * duration of condition

Question 39

median nerve - damage at wrist? - at elbow?

Answer 39

Damage at wrist • 'claw hand' - hyperextension of the metacarpophalangeal joints and flexion at the distal and proximal interphalangeal joints of the 4th and 5th digits • wasting and paralysis of intrinsic hand muscles (except lateral two lumbricals) • wasting and paralysis of hypothenar muscles • sensory loss to the medial 1 1/2 fingers (palmar and dorsal aspects) Damage at elbow • as above (however, ulnar paradox - clawing is more severe in distal lesions) radial deviation of wrist

Question 40

AD condition: if both parents are affected | - what are the chances of an unaffected child? affected heterozygote? affected homozygote?

Answer 40

- 25% chance of unaffected child - 50% chance of affected heterozygous child 25% chance of affected homozygous child

Question 41

mitosis v meiosis | diploid v haploid

Answer 41

mitosis: in somatic cells. results in 2 diploid daughter cells which are the same as the parent cell meiosis: in gametes. results in 4 haploid daughter cells (each cell contains 1 homologue of each chr pair and so are genetically diff) somatic cells: 22 pairs of autosomes + 1 pair of sex chrs - normal chr complement = diploid cells - gametes = 1 copy of each chr = haploid

Question 42

case-control study - describe - outcome measure? - 3 advs - 1 disadv

Answer 42

* Observational and retrospective. * Patients with a particular condition (cases) are identified and matched with controls. Data is then collected on past exposure to a possible causal agent for the condition. * The usual outcome measure is the odds ratio. * Inexpensive, produce quick results * Useful for studying rare conditions * Prone to confounding

Question 43

cohort study - describe - usual outcome measure

Answer 43

• Observational and prospective. • 2 (or more) are selected according to their exposure to a particular agent (e.g. medicine, toxin) and followed up to see how many develop a disease or other outcome. The usual outcome measure is the relative risk.

Question 44

digeorge syndrome - cause - inheritance - what is it - features

Answer 44

AD ``` CATCH22: · C - Cardiac abnormalities · A - Abnormal facies · T - Thymic aplasia · C - Cleft palate · H - Hypocalcaemia/ hypoparathyroidism · 22 - Caused by chromosome 22 deletion ``` Variable presentation: · at risk of viral and fungal infections · parathyroid gland hypoplasia → hypocalcaemic tetany · thymus hypoplasia · T-lymphocyte deficiency/dysfunction DETAILS = a primary immunodeficiency disorder · caused by T-cell deficiency and dysfunction · an example of a microdeletion syndrome (deletion of a section of chr 22)

Question 45

general rules for AR v AD

Answer 45

AR conditions = metabolic (except inherited ataxias) ○ Friedrich's ataxia, ataxia telangiectasia - AR ○ Hunter's, G6PD are x-linked recessive AD are structural (except hyperlipidaemia type 2, hypokalaemic periodic paralysis)

Question 46

ADH - where is it synth? secreted from? - acts on? - whats its aim and how does it do it - what increases its secretion (4) - decreases secretion (3)

Answer 46

- Synth in supraoptic nuclei of hypothal > released by post pit - Function: conserves body water: • Acts on collecting ducts >> promote water reabsorption by inserting aquaporin 2 channels ``` Regulation Increases secretion • extracellular fluid osmolality increase • volume decrease • pressure decrease • angiotensin II ``` Decreases secretion • extracellular fluid osmolality decrease • volume increase temperature decrease

Question 47

actions of | - nucleus, ribosome, rough ER, smooth ER, golgi, lysosome, nucleolus, mitochondria

Answer 47

Nucleus: DNA maintenance, RNA transcription, RNA splicing Ribosome: translates RNA into proteins Rough ER: translate and fold new proteins ``` Smooth ER: synth steroids and lipids Golgi: packages molecules getting secreted Lysosome: breaks down large molecules Nucleolus: ribosome production Mitochondria: aerobic respiration ```

Question 48

bohr effect? haldane effect? chloride shift?

Answer 48

Bohr effect = increasing acidity (or pCO2) means oxygen binds less well to Hb Haldane effect = increase pO2 means CO2 binds less well to Hb NOTES Chloride shift • CO2 diffuses into RBCs • CO2 + H20 ---- carbonic anhydrase -→ HCO3- + H+ • H+ combines with Hb HCO3- diffuses out of cell,- Cl- replaces it

Question 49

what does the adrenal medulla secrete

Answer 49

· Secretes virtually all adrenaline in the body | And a small amount of noradrenaline

Question 50

screening programme criteria 10

Answer 50

1. The condition should be an important public health problem 2. There should be an acceptable treatment for patients with recognised disease 3. Facilities for diagnosis and treatment should be available 4. There should be a recognised latent or early symptomatic stage 5. The natural history of the condition should be adequately understood (including its development from latent to declared disease) 6. There should be a suitable test or examination 7. The test or examination should be acceptable to the population 8. There should be agreed policy on whom to treat 9. The cost of case-finding (including diagnosis and subsequent treatment of patients) should be economically balanced in relation to the possible expenditure as a whole 10. Case-finding should be a continuous process and not a 'once and for all' project wilson and junger criteria

Question 51

what do southern, northern and western blots do

Answer 51

* SNOW (South - NOrth - West) * DROP (DNA - RNA - Protein) Southern: detects DNA Northern: detects RNA Western: detects proteins

Question 52

congenital - toxoplasmosis - CMV - rubella

Answer 52

CMV most common congenital infection in UK toxoplamosis: cerebral calcifications, chorioretinitis Congenital CMV - microcephaly, hepatosplenomegaly and sensorineural hearing loss. - Infected infants will typically be born premature or have a low birth weight Congenital rubella - triad of sensorineural deafness, microphthalmia and congenital heart disease.

Question 53

pre-test probability: what is it? equivalent to what? post-test prob: what is it, eqn same for - pre test and post test odds

Answer 53

Pre-test probability = prevalence of a condition NOTES DETAILS Pre-test probability = The proportion of people with the target disorder in the population at risk at a specific time (point prevalence) or time interval (period prevalence) Post-test probability = The proportion of patients with that particular test result who have the target disorder = post test odds / (1 + post-test odds) Pre-test odds = The odds that the patient has the target disorder before the test is carried out = pre-test probability / (1 - pre-test probability) Post-test odds = The odds that the patient has the target disorder after the test is carried out = pre-test odds x likelihood ratio where the likelihood ratio for a positive test result = sensitivity / (1 - specificity)

Question 54

renin - secreted by? - what does it do? - factors stimulating its secretion - factors reducing its secretion

Answer 54

- secreted by juxtaglomerular cells - hydrolyses angiotensinogen to produce angiotensin I ``` Factors stimulating renin secretion • hypotension causing reduced renal perfusion • hyponatraemia • sympathetic nerve stimulation • catecholamines • erect posture ``` Factors reducing renin secretion drugs: beta-blockers, NSAIDs

Question 55

adrenal cortex: layers and what they release?

Answer 55

Adrenal cortex (mnemonic GFR - ACD) • zona glomerulosa (on outside): mineralocorticoids, mainly aldosterone • zona fasciculata (middle): glucocorticoids, mainly cortisol • zona reticularis (on inside): androgens, mainly dehydroepiandrosterone (DHEA)

Question 56

angiotensin 2 - how is it made - actions: 5

Answer 56

• angiotensin-converting enzyme (ACE) in the lungs converts angiotensin I → angiotensin II • wide variety of actions: • vasoconstriction of vascular smooth muscle >> raised BP • vasoconstriction of efferent arteriole of the glomerulus → increased filtration fraction (FF) to preserve GFR. ○ Remember that FF = GFR / renal plasma flow • stimulates thirst (via the hypothalamus) • stimulates aldosterone and ADH release increases proximal tubule Na+/H+ activity

Question 57

aldosterone: released by? in response to (3) - causes?

Answer 57

Aldosterone • released by zona glomerulosa in response to raised angiotensin II, potassium, and ACTH levels • causes retention of Na+ in exchange for K+/H+ in distal tubule

Question 58

relative risk RR increase/decrease EG if we look at a trial comparing the use of paracetamol for dysmenorrhoea compared to placebo we may get the following results Total number of patients Experienced significant pain relief Paracetamol 100 60 Placebo 80 20

Answer 58

RR = EER /CER RR reduction/increase = (EER-CER) / CER Experimental event rate, EER = 60 / 100 = 0.6 Control event rate, CER = 20 / 80 = 0.25 Therefore the relative risk ratio = EER / CER = 0.6 / 0.25 = 2.4

Question 59

b cells | plasma cells

Answer 59

b cells: humoral immune response. hyperacute organ rejection plasma cells: differentiate from b cells and produce lots of Ab specific to an antigen

Question 60

helper t cells | cytotoxic t cells

Answer 60

both: cell mediated immune response. acute and chronic organ rejection. recognises antigens presented by mhc class 2 molecules helpet: expresses cd4 cytotoxic: expresses cd8. induces apoptosis in virally infected and tumour cells. MHC class 1

Question 61

levels of evidence 1a to IV | and grading recommendations A-C

Answer 61

Levels of evidence • Ia - meta-analysis of randomised controlled trials • Ib - at least one randomised controlled trial • IIa - at least one well designed controlled trial which is not randomised • IIb - at least one well designed experimental trial • III - evidence from case, correlation and comparative studies • IV - evidence from a panel of experts Grading of recommendation • Grade A - based on evidence from at least one randomised controlled trial (i.e. Ia or Ib) • Grade B - based on evidence from non-randomised controlled trials (i.e. IIa, IIb or III) Grade C - based on evidence from a panel of experts (i.e. IV)

Question 62

``` Atrial natriuretic peptide sec by MAIN ACTION, OTHER ACTIONS antagonises? degraded by? ```

Answer 62

Basics • secreted mainly from myocytes of right atrium and ventricle ○ secreted by both atria (right >> left) • Sec in response to increased blood volume • 28 amino acid peptide hormone, which acts via cGMP • degraded by endopeptidases MAIN ACTION: VASODILATION Actions • natriuretic, i.e. promotes excretion of sodium • lowers BP antagonises actions of angiotensin II, aldosterone

Question 63

variance what is it relationship to standard deviation

Answer 63

Variance (measure of the spread of scores away from the mean) = square of standard deviation

Question 64

vitamin K - action - how long does it take for effect 2 causes of deficiency

Answer 64

Acts as a cofactor in carboxylation of clotting factors 2, 7, 9 and 10 Notes Details a fat-soluble vitamin Clinically, it is used to reverse the effects of warfarinisation • takes up to 4 hours for there to be a change in the INR Vitamin K deficiency • fat-soluble: so levels may fall in conditions affecting fat absorption Can also occur after prolonged use of broad-spectrum antibiotics by eliminating the gut flora

Question 65

TH1 - involved in (2), secrete? | TH2 involved in (1), secrete?

Answer 65

Th1 • involved in the cell-mediated response and delayed (type IV) hypersensitivity • secrete IFN-gamma, IL-2, IL-3 Th2 • involved in mediating humoral (antibody) immunity • e.g. stimulating production of IgE in asthma secrete IL-4, IL-5, IL-6, IL-10, IL-13